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An analysis of asecna strategy for adopting CNS/ATM
Citation preview
Will ASECNA meet the needs of African
air navigation for the 21st century?
An analysis of ASECNA strategy for adopting advanced CNS/ATM
Department of Air
Transport Management
MSc THESIS
Academic year 2004-2005
Francis Fabien Ntongo Ekani
Supervisor: Rodney Fewings
CRANFIELD UNIVERSITYSCHOOL OF ENGINEERING
DEPARTMENT OF AIR TRANSPORT
MSc THESIS
Academic year 2004 - 2005
Will ASECNA meet the needs of African
air navigation for the 21st century?
An analysis of ASECNA strategy for adopting advanced CNS/ATM
By Francis Ntongo
Supervisor: Rodney Fewings
This thesis is submitted in partial fulfilment of the requirements for the degree of Master of Science
©Cranfield University 2005. All rights reserved. No part of this publication may be reproduced
without the written permission of the copyright owner
To My Parents
Abstract
This MSc thesis aims at investigating the rationale of implementing CNS/ATM1
systems in ASECNA area, a region of the African continent. The question of whether
ASECNA’s modernisation strategy will respond to African air navigation’s future
needs is essential to the region, as a performing system is a prerequisite for the
viability of air transport activities.
The study analyses the situation of service provision in the region and highlights the
needs and the priorities. It also assesses the suitability of future air navigation
systems, their ability to respond to these needs, and it provides an analysis of
ASECNA’s strategy.
The region is characterised by an insignificant level of traffic at a global scale. Local
air transport industry needs help to reduce its costs, as the majority of carriers are
struggling to survive in a context of combined low demand, and very high fuel prices.
There are a high number of air navigation incidents relatively to the level of traffic.
That is due to an inefficient system based essentially on conventional navigation
systems, which are very often unreliable and underperforming. The research reveals
the predominance of Safety, Efficiency and airspace Fragmentation as the primary
performance drivers for evolving the system. ASECNA is responding to its users’
needs by implementing future air navigation systems. CNS/ATM trials suggest that
the technology can respond to regional priorities as they bring greater efficiency,
increased capacity and safety, and enhanced cross border cooperation and cost
effectiveness. They are also suitable for inhospitable areas like in ASECNA.
Local airlines have limited means to upgrade their old fleets. Foreign carriers operate
high yield routes and generate 80 per cent of ASECNA’s revenues and operate young
well equipped aircraft. Therefore, the agency has developed a dual strategy, by
maintaining ground-based systems for small local carriers on domestic routes, while
introducing CNS/ATM systems on main areas of routing.
ASECNA will make the new systems available to its users, but it will not necessarily
be cost effective. However, the success of the implementation process also depends
on the ability of member states to upgrade and harmonise their legislations on time.
The slowness of legislative procedures and the lack of harmonisation in Africa will
delay the benefits, which is damaging to the industry.
1 Air Traffic Management supported by three components: Control, Navigation and Surveillance
Aéroport Du Cameroun (ADC)
Etablissement National de la Navigation
Aérienne (ENNA, Algeria)
Acknowledgement
I’d like to thank Rodney, my supervisor, for his constant support, his wise and
constructive critics and all the advices he gave me and that contributed to the success of
this thesis. Andy Foster and Simon Place also gave me a decisive support.
I’ll also like to thank Professor Fariba Alamdari, the Head of Air Transport Group, for
having made me to understand what management is about: Always being Positive and
getting the best from People.
Special thank to ASECNA for their precious and invaluable support throughout the
project, and for welcoming me during one week at their Head Quarter in Dakar,
Senegal:
Youssouf Mahamat, Director General
Amadou Guitteye, Director of Operations
Wodiaba Samake, Head of training office
And
Marafa Sadou, Special adviser to the director of operations
Diallo amadou Yoro, Head of Normalization office
Hilaire Tchicaya, Head of Aeronautical Telecommunication office
Ngoue Celestin, Head of Air Navigation
Sacramento Martin, Engineer, office of Statistics
Edmond Hocke Nguema-Biteghe, Head of Network Operations
Armand Boukono, Engineer, Normalization office
Ndobian Kitagoto, Engineer, Meteorology office
Aviation companies
Air Benin, Air France KLM
Air Inter Cameroon
Air Madgascar
Air Senegal international
Bellview Airlines, Cameroon Airlines
iii
Table of content
Abstract iAcknowledgement iiTable of Content iiiList of figures vList of tables viiiGlossary ix
Chapter 1 Introduction to thesis page 1
1.1 Background 11.2 Research questions 31.3 Objectives 41.4 Methodology 41.5 Structure of thesis 71.6 Data sources 71.7 Key assumption 71.8 Choice of performance measures 81.9 Summary 9
Chapter 2 ASECNA’s region Air Transport Industry 10
2.1 Economic characteristics 112.2 Transport infrastructure 132.2.1 Roads 132.2.2 Railways 132.2.3 Ports 142.3 Air Transport Industry 142.3.1 Airport Infrastructure 152.3.2 Airlines 162.3.3 Fleet 172.4 Regulatory 252.5 Air Travel Demand 262.6 Conclusion 32
Chapter 3 Air navigation Performance Review 34
3.1 Introduction 343.2 Airspace organization 343.2.1 Description of ASECNA’s strategy 343.2.2 Fragmentation 363.3 Traffic 383.3.1 Airport activity 383.3.2 En-route traffic 403.4 Delays 443.5 Impact of future trends 443.5.1 Prospects 44
iv
3.5.2 Impact on runway capacity 453.5.3 Impact on en-route capacity 463.6 Traffic complexity 473.7 Safety 483.7.1 Air Proximities 483.7.2 Users' claims 493.7.3 Birdstrikes 493.7.4 Safety Review System 503.8 Efficiency 503.8.1 Flight efficiency 503.8.2 Fuel efficiency 513.9 Cost effectiveness 543.9.1 Navigation charges 543.9.2 Air Navigation Costs 553.10 Cooperation 573.11 Training 593.12 Financing 593.13 CNS and Aviation weather management issues 603.13.1 Shortcomings of conventional systems 603.13.2 ASECNA's systems' performance 643.15 Conclusion 69
Chapter 4 CNS/ATM systems and concepts 70
4.1 Introduction 704.2 Suitable CNS/ATM systems for ASECNA 724.2.1 Geographic characteristics 724.2.2 Efficiency 724.2.3 Capacity for Safety 734.2.4 Surveillance 734.3 Study of selected systems 734.3.1 Communications 734.3.2 Navigation 834.3.3 Surveillance 924.3.4 Air Traffic Management 974.4 Transition phase 984.6 Affordability 994.7 Conclusion 100
Chapter 5 Analysis of ASECNA’s modernization strategy 102
5.1 Description of the strategy 1025.1.1 Communications 1025.1.2 Navigation 1035.1.3 Surveillance 1035.1.4 Systems on board the aircraft 1055.1.5 Aviation weather 1055.1.6 Air Traffic Management 106
v
5.1.7 Cooperation 1075.1.8 Training 1105.1.9 Financing 1105.1.10 Implementation schedule up to 2015 1125.2 Analysis 1135.3 Conclusion 115
Chapter 6 Recommendations and Conclusion 117
References 122
Appendix 1 Presentation of ASECNA 126
Appendix 2: Ground Based Navigation Systems Principles 1301 How the VOR works 1302 How DME works 1323 How ILS works 1334 Multilateration 134
Appendix 3 WGS-1984 136
Appendix 4 ASECNA’S Telecommunications Network 137
Appendix 5 Air Traffic Projected Growth by world region 138
Appendix 6 ICAO’s Navigation SARPs 139
Appendix 7 ASECNA’s Satellite Navigation Circuits 140
Appendix 8 ASECNA’S ATS/Direct Speech Network 141
Appendix 9 CNS/ATM: Drivers and Origins 142
List of Figures
Chapter 1
Figure 1.1 Short term evolution of crude oil 2
Figure 1.2 Analytical Framework of ASECNA’s performance analysis 5
Chapter 2
Figure 2.1 ASECNA area in this report 10
vi
Figure 2.2 Share of population and GDP by country 12
Figure 2.3 Stakeholders 15
Figure 2.1 Repartition of Aircraft types in Africa 18
Figure 2.2 Intra African market Fleet (Jets + Turbo Propellers) 19
Figure 2.3 African fleet annual utilization 20
Figure 2.4 African fleet Evolution from 2003 to 2023 21
Figure 2.5 RPK, ASK (Billion) and Passengers load factors in Africa 21
Figure 2.6 Trend in Aviation fuel cost 23
Figure 2.7 Yields and Unit costs in Key markets 23
Figure 2.8 African Airlines 1 Operating costs (Unit cost $ per tonne per Km) 24
Figure 2.9 Regional share of global international air passenger traffic 26
Figure 2.10 Evolution of passenger traffic (1994-2003) 27
Figure 2.11 Average Airport Passenger Traffic (2000-2004) 28
Figure 2.12 Evolution of Cargo traffic (1994-2003) 31
Chapter 3
Figure 3.1 ASECNA’s Flight Information Regions 37
Figure 3.2 Number of flights from 1993 to 2003 38
Figure 3.3 Number of aircraft movements at 15 key airports 39
Figure 3.4 Areas of Routing 41
Figure 3.5 Average number of flights controlled per hour and per controller 43
Figure 3.6 Projected growth over the next decade 45
Figure 3.7 Projected runway occupancy in ASECNA’s main airports 46
Figure 3.8 Projected controllers’ productivity in 2015 47
Figure 3.9 Evolution of Air Proximities 48
1 Flight Equipment comprises maintenance, insurance, and rental. The others operating expenses are not mentioned here. But it’s interesting to note that administration unit costs for non efficient airlines are extremely high, almost twenty times higher than an efficient airline’ unit costs.
vii
Figure 3.10 Evolution of incidents during the last six years 49
Figure 3.11 Flight paths between Douala and Dakar 51
Figure 3.12 The different phases of a flight 52
Figure 3.13 Evolution of air navigation charges 54
Figure 3.14 Personnel, ANS and transport costs from 1996 to 2003 55
Figure 3.15 Evolution of the average cost per flight from 1996 to 2003 56
Figure 3.16 Evolution of en route revenues from 1996 to 2003 57
Figure 3.17 Regional fragmentation of ATM sectors 58
Figure 3.18 Financial results from 1994 to 2003 59
Figure 3.19 OPMET availability rate 68
Chapter 4
Figure 4.1 Communication links in ASECNA 74
Figure 4.2 CPDLC test message 75
Figure 4.3 Estimated capacity gained as a function of % of CPDLC equipage 76
Figure 4.4 Aeronautical telecommunications network concept 82
Figure 4.5 Comparison between EGNOS and GPS 85
Figure 4.6 Lateral and Vertical Total System Error 87
Figure 4.7 Comparison between RNAV, RNP and conventional navigation 89
Figure 4.8 Atlanta SID trials: Non RNAV tracks 90
Figure 4.9 Atlanta SID trials: RNAV tracks 90
Figure 4.10 Projected RNP-RNAV capable aircraft 91
Figure 4.11 ADS-B operational capabilities 94
Figure 4.12 ADS-B performances Vs Radar 96
Chapter 5
Figure 5.1 Classification of CNS/ATM expenditure 112
Figure 5.2 Possible Airspace redesign by 2030 115
viii
Appendices
Statutory structure 128
External representations’ organisation chart 129
VOR station 131
World Geodetic System 136
ASECNA’s Telecommunication Network 137
ASECNA’s Satellite connectivity 140
ASECNA’s ATS/DS network 141
Evolution of CNS/ATM implementation 145
List of Tables
Table 2.1 Comparative GDP and Population 11
Table 2.2 Situation of aircraft operated in the world 19
Table 2.3 Daily passenger traffic between city pairs 29
Table 2.4 International traffic at major regional airports 30
Table 3.1 The main airstream in ASECNA 40
Table 3.2 Traffic by FIR 40
Table 3.3 Average traffic density from 2001 to 2003 42
Table 3.4 Average traffic density by 2015 46
Table 3.5 Average ANS cost per flight in Europe, ASECNA and the USA 56
Table 3.6 Equipments availability 65
Table 3.7 Air circulation control: controlled routes 67
Table 4.1 Workload reduction as a function of aircraft equipage 77
Table 4.2 Delays reduction as function of aircraft equipage 77
Table 4.3 Results for lateral and vertical accuracy with EGNOS 87
Table 4.4 Results for availability during trials Vs ICAO’s SARPs 87
Table 4.5 ICAO’s SARPs for lateral and vertical accuracy 87
ix
Glossary
A
ACC Area Control Centre
ADS Automatic Dependent Surveillance
ADS-B Automatic Dependent Surveillance Broadcast mode
ADS-C Automatic Dependent Surveillance Contract mode
AFI Africa Indian ocean area
AFS Aeronautical Fixed Service
AFTN Aeronautical Fixed Telecommunication Network
AIS Aeronautical Information Service
AMS(R) S Aeronautical Mobile-Satellite (R) Service
AMHS Aeronautical Mobile Handling System
AMSS Aeronautical Mobile-Satellite Service
ANSP Air Navigation Service Provider
AOC Airline Operation Centre
APIRG AFI Planning and Implementation Regional Group
APV Approach with vertical guidance
AR Area of routing
ASECNA Agency for Security, Aerial Navigation in Africa and Madagascar
ASM Airspace Management
ASK Available Seat Kilometre
ATC Air Traffic Control
ATFM Air Traffic Flow Management
ATM Air Traffic Management
ATN Aeronautical Telecommunication Network
ATS Air Traffic Services
ATS/DS Air Traffic Services Direct Speech
C
CDM Collaborative Decision Making
CDMA Code Division Multiple Access
CFIT Controlled Flight Into Terrain
x
CNS/ATM Communications, Navigation, Surveillance / Air Traffic Management
CPDLC Controller pilot data link communications
D
DECCA A low frequency hyperbolic radio navigation system
DFIS Data Link Flight Information Services
DME Distance Measuring Equipment
E
EGNOS Eurpean Geostationary Navigation Overlay Service
EUR European Region
EUROCAT Thales ATM (Commercial organisation) air traffic management
automation product
F
FAF Final Approach Fix
FANS Future Air Navigation Systems
FIR Flight Information Region
FDPS Flight Data Processing System
FL Flight Level
FMS Flight Management System
G
GLONASS Global Orbiting Navigation Satellite System (Russian Federation)
GNSS Global Navigation Satellite System
GPS Global Positioning System (United States)
H
HF High Frequency
HFDL High Frequency Data Link
I
IATA International Air Transport Association
ICAO International Civil Aviation Organization
IFR Instrument Flight Rules
ILS Instrument Landing System
xi
INS Inertial navigation system
ITU International Telecommunication Union
L
LORAN Long Range Air Navigation
M
MET Meteorological services for air navigation
METAR Aviation routine weather report
MLS Microwave Landing System
MODE S Mode Select
N
NDB Non-directional beacon
NOTAM Notice To Airmen
NPA Non-precision approach
NSE Navigation System Error
O
OPMET Operational Meteorology
P
PDN Paquet data Network
PIRG Planning and Implementation Regional Group
R
RIMS Ranging Integrity Monitoring Station
RNAV Area Navigation
RNP Required Navigation Performance
RPK Revenue Passenger Kilometre
RTK Revenue Tonne Kilometre
RVSM Reduced Vertical Separation Minimum
S
SAM South American Region
SARPs Standards and Recommended Practices
SAS Scandinavian Airways
xii
SAT South Atlantic
SATCOM Satellite Communication
SBAS Satellite-based augmentation system
SID Standard Instrument Departure
SIGMET Significant Meteorological event
SIGWX Significant Weather
SITA Société Internationale de Télécommunications Aéronautiques
SSR Secondary Surveillance Radar
T
TACAS Terminal Access Controller Access Control System
TACAN Tactical Air Navigation
TAF Terminal area forecast
TDMA Time Division Multiple Access
TMA Terminal Manoeuvring Area
TSE Total System Error
V
VDL VHF Data Link
VFR Visual flight rules
VHF Very High Frequency
VOR VHF Omnidirectional Radio Range
W
WGS-84 World Geodetic Reference System 1984
1
Chapter 1 : Introduction to Thesis
The aim of this chapter is to introduce the research topic and to present the objectives and the methodology used to respond to the research question.
1.1. Background
Agency for Air Navigation Safety in Africa (ASECNA1) is a regional publicly held
establishment that provides navigation services to 15 West and Central African
Countries2, plus Madagascar and the Comoro islands in the Indian ocean.
The region is relatively poor. Economic characteristics are those of developing
countries. Some of the less advanced countries are located there.
ASECNA covers an area of 16 million square kilometres3, most of which is unoccupied
and dominated by the Sahara desert, oceans and forests.
The Air Transport Industry has changed significantly over the past decade. These
changes were dictated by a combination of factors, mainly operational and financial,
following a succession of crisis4. The airline industry is increasingly sensitive to the
cost of doing business.
Efficiency
Air carriers demand direct routes, flight level optimization, efficient in-flight and
improved en-route fuel5 consumption. Figure 1.1 below shows the projected upwards
evolution of crude oil prices. That means airlines’ fuel bill will significantly increase.
Cost reduction is one aspect of mitigating the effects of fuel high price. It explains why
airspace users want more efficiency. It is one of the factors that led them to incite
suppliers, such as air navigation service providers (ANSP) to improve their
effectiveness and the quality of service provision.
1 In the present study designates both the agency or the geographic region2 Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Congo Brazzaville, Equatorial Guinea, Gabon, Ivory Cost, Mali, Mauritania, Niger, Senegal, Togo. France is also an observer member.3 Equivalent to almost 66 times Great Britain size.4 September Eleven, SARS, Bird Flu, Second Golf War…5 Crude oil price was around 50 dollars per barrel in 2005
Chapter 1 Introduction to Thesis
2
Figure 1.1: Short-term evolution of crude oil prices
Source: IATA, 2006
Capacity
Air travel and air traffic are continuously growing. The number of aircraft movements
has increased by 5.3 per cent per year on average over the past 15 years in ASECNA
region, which is in line with worldwide trends. The growth is forecast to continue at an
estimated yearly pace of 5 per cent. That activity means an increasing pressure will be
put on airports and air navigation systems, which may raise airspace and airport
capacity concerns.
Safety
Safety records are worrying in Africa. The continent represents only about 3 per cent
of global traffic. Nevertheless, statistics show that almost one third of fatal accidents
over the past ten years occurred in Africa according to IATA.
Chapter 1 Introduction to Thesis
3
Air Transport is a catalyst for development and trade. Efficiency, Capacity and Safety of
air navigation systems are therefore strategic components for a viable regional6 air
transport industry and growing national economies.
The important question is whether ASECNA will manage to overcome the current and
future challenges. Will they respond to users’ requirements while delivering a safer
service, in the interest of regional air transport?
The agency has embarked on a modernisation programme since 1994. It is
implementing modern air navigation systems, known as Future Air Navigation Systems
(FANS) or CNS/ATM (Control, Navigation, Surveillance and Air Traffic
Management).
CNS/ATM systems are a complex and interrelated set of technologies and concepts
largely based on satellite communication. They are the response brought forward by the
aviation community, under the aegis of the International Civil Aviation Organisation
(ICAO), in response to the challenges described above. Regional work groups have
been put in place to coordinate efforts. ASECNA is member of AFI7 Planning and
Implementation Regional Group (APIRG), which regroups African and Indian Ocean
countries
The thesis intends to investigate current systems’ performance in ASECNA. It
highlights regional shortcomings and needs, and examines the agency’s modernisation
strategy, CNS/ATM adopted solutions, and their implications on service provision for
the next 15 years.
1.2. Research Questions
The main research question of the thesis is: Will ASECNA meet the needs of African
Air Navigation for the 21st Century?
Responding to that question requires that the following intermediate questions are dealt
with:
6 ASECNA region7 Africa and Indian Ocean
Chapter 1 Introduction to Thesis
4
1. What are the needs and the priorities of African Air Navigation for the 21st
century?
2. Are CNS/ATM systems the suitable tool with regard to regional characteristics?
3. Will ASECNA’s modernisation strategy respond effectively to the needs?
1.3. Objectives
The objectives of the study are to:
1. Examine the state and the performance of air navigation service provision in
ASECNA
2. Study the potential benefits of CNS/ATM systems to the region
3. Analyse ASECNA’s modernisation plans
1.4. Methodology
This research is based on an analytical approach to assessing ASECNA’s capability to
respond to airspace users’ needs and requirements and regional air transport’s interests.
To answer to the first research question that aims at defining the needs and the
priorities of African Air Navigation, we process as follows:
First, the region’s air transport industry is assessed. This is done by examining local air
transport characteristics:
1. Analysis of air travel demand
2. Assessment of air carriers types
3. Examination of air carriers performance
4. Examination of airport and alternative transport infrastructures
5. Overview of regulations and the factors that influence air traffic.
Secondly, the air navigation system’s performance is studied, by analysing key
performance areas and related indicators:
Chapter 1 Introduction to Thesis
5
1. Traffic demand, Capacity, Delays
2. Complexity, Safety, Aircraft proximities
3. Performance of CNS and Met systems.
4. Fragmentation, Cost Effectiveness
5. Flight efficiency
6. Cooperation.
The analytical framework used is described in figure 1.2 below. The structure is based
on a model developed by the Eurocontrol Performance Review Commission to assess
European Air Traffic Management performance. It has been adapted for the present
study.
Figure 1.2: Analytical Framework of ASECNA’s performance analysis
Source: Eurocontrol, Performance Review Report 8, 2005
Complexity
Trafficdemand
Capacity
Fragmentation
AIRPROX
CNS Met Systems
Availability
Delays
Productivity
Service provision
cost
Safety
CostEffectiveness
Flight Efficiency
Cooperation
ASECNA performance
PerformanceDrivers
Performance indicators
Drivers
ANS Key performance Areas
Chapter 1 Introduction to Thesis
6
Finally, the impact of traffic growth is estimated. We apply forecasted growth rates to
current data, in this case 2003.
To answer to the second research question, which aims at determining the relevance of
CSN/ATM systems in ASECNA, we adopt the following method:
Based on the system’s deficiencies and local characteristics drawn from the previous
performance analysis:
1. Identification of potentially suitable CNS/ATM technologies and systems based on
FANS performance during worldwide trials. These trials are performed under certain
geographic and operational conditions; some of them match ASECNA area’s
characteristics.
2. Their affordability is assessed
At last, the third research question is dealt with as follows:
1. Assessment of the technology solutions adopted
2. Assessment of the implementation process, and we analyse the strategies in the
areas listed below:
a. Communication
b. Navigation
c. Surveillance
d. Met
e. Air Traffic Management
f. Training
g. Programme financing
h. Cooperation
3. Assessment of the timeframe by confronting the predicted timetable and realized
projects.
Chapter 1 Introduction to Thesis
7
When quantifiable data are not available, interviews allow to have an idea of the
situation. Interviewees are ASECNA’s high profile staff, airlines directors, and other
ANSPs’ personnel.
1.5. Structure of Thesis
The choice of performance areas is discussed in chapter 1. The overview of ASECNA
region’s air transport industry is discussed in Chapter 2. An insight of regional
characteristics is given, which provides a better understanding of the operational
environment and the context, as well as the importance of a performing air navigation
system for the region. A detailed analysis of air navigation systems’ performance is
provided in Chapter 3. Local navigation characteristics are discussed, and predefined
performance areas presented in chapter 1 are examined. That allows highlighting the
areas that require improvements and to define what should be the priorities for the
region. Chapter 4 presents CNS/ATM systems and concepts and looks at their potential
benefits, with regard to local characteristics. Finally, the strategy adopted by the agency
to respond to those priorities is examined in chapter 5.
1.6. Data Sources
The instruments for this study include a one week visit to ASECNA’s headquarter in
Dakar, Senegal, to collect data and documents, to discuss with professionals involved in
daily operations and to observe the actual state of the implementation of the strategy on
the ground. Telephone interviews, email-statements, internet documentation are
intensively used. Key internet documents come from ICAO, ASECNA, IATA, and
CANSO8’s CNS/ATM related literature.
1.7. Key Assumptions
The geographic boundaries of the study are clearly the region covered by ASECNA.
However, as ASECNA9 is part of the wider geographic entity, the study of this region
naturally implies to investigate its interactions with the neighbourhood.
8 Civil Air navigation Services Organisation9 Seen here as a region, not the organization itself
Chapter 1 Introduction to Thesis
8
A key assumption in the study is that average economic and air traffic prospects that are
applicable to the African continent are applicable to ASECNA. This is a sensitive
approach as the economic characteristics of the region are similar to the continent’s
patterns. However, the average growth figures may be driven up by air transport leading
countries. In particular, air transport is less developed in ASECNA then Southern,
Eastern Africa, and North Africa.
Another key assumption is that the relative importance of individual countries’ air
transport performance is frozen over the period studied. Therefore, the relative
importance of airports size and spatial distribution of traffic flows within the region is
supposed to remain unchanged.
1.8. Choice of performance indicators
A large number of indicators could be used to assess ASECNA’s performance. How
ever, for this study, several factors influenced the choice of indicators:
The availability of data: several other indicators could have been used but ASECNA
does not collect the corresponding data. Moreover, some chosen indicators could have
been broken down into more detailed data, but that has not been possible.
The effectiveness of chosen indicators in assessing an ANSP’s performance:
Safety, Capacity, Flight efficiency, Cost Effectiveness, cross border cooperation are
aspects of an ANSP operation that effectively evaluate the quality of service provision.
Safety
Safety performance measures are hardly available in ASECNA. However, indicative
incidents reports are used to assess the safety level. A comparison with other Regions’
safety records with respect to the level of traffic gives an idea of ASECNA’s
performance.
Capacity
Capacity is closely related to delays and the level of traffic. Although delays data are
not available, interviews allow having an idea of influent factors.
Chapter 1 Introduction to Thesis
9
Flight Efficiency
The availability of a maximum number of direct routes and the possibility to chose
optimum flight levels are crucial to airlines as it allows reducing their fuel bill.
Cost effectiveness
The bill paid by airlines for service provision depends on ASECNA’s ability to maintain
low operating costs.
Cooperation
The level of technical and political cooperation indicates how states and ANSPs work
together to avoid unnecessary costs to airlines, and make the airspace as seamless as
possible.
1.9. Summary
This chapter laid the foundations for the thesis. It introduced the research problem and
questions: Will ASECNA meet the needs of the African Air Navigation for the 21st
century? In addition, what are the problematic and the challenges related to the
achievement of that mission? The research was justified, and the methodology, based on
an analytical approach was detailed. Performance indicators have been presented and
discussed. Key assumptions were presented.
10
Chapter 2: ASECNA’s Air Transport Industry
The aim of this chapter is to find out the region’s air transport industry’s characteristics.
This is an important step as it helps to understand in which environment ASECNA
evolves, and the factors that may influence its activities. Further details on ASECNA as
an organization and its history are included in appendix 1.
Figure 2.1: ASECNA area in this report
Source: ASECNA
Chapter 2 ASECNA’s Air Transport Industry
11
2.1 Economic Characteristics
ASECNA comprises developing countries, mainly located in western or Central Africa,
except Madagascar and the Comoros Islands located in the Indian Ocean (See map
above). Their Economies are relatively weak. Mali, Niger, Chad, Burkina Faso Togo
and the Central African Republic (CAR) are among the poorest country in the world.
The general picture is one of underdevelopment, political instability, economic
volatility and high poverty. Comparative Gross Domestic Products and populations
between ASECNA, the world average and UK’s performance reflect that situation
(Table below).
Region GDP
($ billion)
GDP /Capita
($ thousand)
Population
(million)
ASECNA1 93 1.7 141
WORLD 43920 9.5 6,526
UK 2218 31 60
Table2.1: Comparative GDP and populations;
Source: CIA World fact book, 2006
The region accounts for just 0.2 per cent of world GDP. But in contrast to its low share
of economic activity worldwide, as the table above shows it, 141 million people live in
ASECNA, which is 2.2 % of world population. That combination of low input and high
population means the GDP per capita in ASECNA is the lowest among the world
regions (1700 dollars). UK for instance is 24 times wealthier, and its GDP per capita is
26 times ASECNA’s average. 46 per cent of the population lives under the poverty line
in the region.
Countries in ASECNA remain to a large extent producers of raw materials. They export
agricultural goods such as coffee, cocoa and cotton, or mineral such as crude oil and
copper. Trade exchanges in ASECNA region tend to be dominated by agricultural
exports.
1 Data compiled from CIA world Fact book 2006
Chapter 2 ASECNA’s Air Transport Industry
12
However, economic development is not homogeneous within the region. Noticeable
disparities between countries exist. For example, while Equatorial Guinea represents
only 0.4 per cent of regional population, it accounts for 8.3 per cent of GDP. In
contrast, Madagascar that contains 13 per cent of total population accounts only for 4.9
per cent of regional GDP. (Figure 2.2)
Figure 2.2: Share of Population and GDP by country
02468
101214161820
Mad
gasc
ar
Ivory
Coa
st
Camer
oon
Burkin
aNige
r
Seneg
alMal
i
ChadBen
inTog
oCAR
Congo
Maurit
ania
Gabon
Comor
os
Equat
orial
Guin
ea
(pe
rce
nta
ge
)
% Population %GDP
Source: CIA fact book 2006
Ivory Coast, Cameroon, Senegal, Gabon and Equatorial Guinea account for almost 60
percent of ASECNA GDP and one third of the population, while Comoros, Niger,
Mauritania, Togo, and CAR own 9.3 per cent of GDP and host 20 per cent of
population.
Regional integration processes are on the way. ASECNA members countries located
in West Africa are part of ECOWAS (Economic Community of West African States).
Those located in Central Africa are members of CEMAC (Central Africa Economic and
Monetary Union). The level of integration varies significantly. The ECOWAS is much
more advanced than the CEMAC. But the two entities are confronted to the economic
Chapter 2 ASECNA’s Air Transport Industry
13
disparities described above, which slow the pace of integration. The lack of a real
political will in CEMAC, or persisting political instability and civil wars in key
countries such as Ivory Coast, and the Republic of Congo have also had a damaging
impact on regional economic and political integration.
In other respects, bad Governance is a common practice at the state level and in public
companies. States continue to own a high number of companies in strategic sectors such
Telecommunications, Water, Energy and Transports, although privatisations are
spreading across the region, mainly on the basis of International Monetary Funds
Recommendations (IMF). It is generally admitted that state ownership, “poor
management and monitoring, and anti-competitive arrangements have bred corruption
in Africa” and particularly in the ASECNA area (Morrell, 2005)
These factors, combined with the low level of investments (Foreign Direct Investments
are among the lowest in the world), contribute to explain the underdevelopment of basic
infrastructures, particularly in the transport sector.
2.2 Transport infrastructure
2.2.1 Roads
Roads are the predominant mode for freight and passenger transport in Africa (World
Bank, 2005). But within individual countries, very often, only the main cities are linked
by paved roads. Regional interconnection is very limited. There are only 39,000
Kilometres of paved roads in the entire region, which represents 18 percent of total road
network. Moreover, these roads are often in a relatively bad state due to poor
maintenance. In comparison, UK alone has 392,931 Kilometres of highways, which is
ten times more. That situation renders economic exchanges very difficult and slows
their intensity as well as it limits regional integration.
2.2.2 Railways
Railway links are very poor or do not exist within and between countries. Two third of
the actual rail infrastructure were inherited from the colonial period (OEDC, 2005,
P.22).
Chapter 2 ASECNA’s Air Transport Industry
14
There are only 8228 Kilometres of railways in ASECNA countries (17300 in the UK).
Some states such as Niger, Chad, Equatorial Guinea, Comoros, and CAR have simply
no railway infrastructure, which means their economic activity depends heavily on the
road system.
2.2.3 Ports
There are a dozen key ports in ASECNA. The most important of them is Dakar, with
about 10 millions tonnes of goods. The essential of ASECNA countries trade activities
is carried out through these ports. For instance, 98 per cent of exchanges between
Cameroon and the outside world are done through Douala autonomous port, with about
5.2 millions tonnes per year (Mission Economique, 2006)
But, the reliability and the speed of exchanges of goods and mobility of people is a
crucial factor for regional integration. Given the under performance of road, and rail
systems, and the slowness of sea transport, the availability of an adequate air transport
infrastructure is therefore of paramount importance for ASECNA countries as they try
to integrate into the world economy.
2.3 Air Transport industry
A developed air transport industry is a driving force for economy, and a catalyst for
development and trade. It facilitates exchanges between countries in which air
transport substitutes, the road and rail systems are underdeveloped.
Passenger aviation is the principle mean of transport for business and tourism travellers.
Airports link the movement of passengers and goods to national economies; they serve
as a primary hub for the tourism industry, and as key logistical centre for international
trade.
Stakeholders in ASECNA are the states, airlines, ANSPs, airports and international
institutions. The study focuses on the relation between ANSPs and other stakeholders
(Figure 2.3).
States are represented by civil aviation authorities and Governments. They make air
transport policies, on the basis of strategic objectives, through legislations applying to
all the others stakeholders in the region.
Chapter 2 ASECNA’s Air Transport Industry
15
Airlines are of different types: International, Domestic, and Regional. Both ASECNA
originated airlines and the others are considered.
Airports are divided into main and secondary airports.
The region only air navigation service provider is ASECNA. The institution has links
with others neighbouring ANSPs.
Figure 2.3: The stakeholders2
2.3.1 Airport Infrastructure
Main Airports
The airport infrastructure (airstrips, air terminals, aircraft hangars) of ASECNA member
states comprises about 25 international airports (2400 to 3500 m of tarred runways)
regularly used. The main airports are Dakar, Abidjan, Douala, Libreville, Brazzaville
and Antananarivo. They are served by major regional, continental and intercontinental
airlines. The service provided is acceptable, but is far from being good.
The airport sector is not free from financing, safety and security problems. Built for the
most part in the 1960s and 1970’s, they present deficiencies. These vary from State to
State. Runways are generally in a bad state, taxiways and parking areas are often
2 All the stakeholders are not taken into account: Ground Handling, Maintenance, Catering… etc
Air Navigation Provider
ASECNA
AirlinesDomesticRegional
International
Policy MakersGovernmentsCivil Aviation
AuthoritiesLegislationsInstitutions
Policy Objectives
AirportsMain
Secondary
Other ANSProviders
Cooperation
Performance
Air TravelCustomers
Chapter 2 Asecna’s Air Transport Industry
16
unsuitable; passenger terminals are cramped or saturated in peak hours. There are
insufficient cargo hangars, refrigerating warehouses and fencing (African Union, 2005).
There are needs for the updating of these installations to meet international standards.
The inexistence of airport fences or in disrepair poses serious security and safety
problems.
Secondary Airports
The region counts about 150 domestic airports (runways of 1000 to 2000 m, usually
unpaved) and about 200 other national aerodromes (poorly maintained), with for several
of them inexistent traffic. These airports do not often have adequate navigation aids, or
basic airport commodities, which constrains their accessibility.
2.3.2 Airlines
In West Africa, and particularly in ASECNA, the liquidation of Air Afrique after 40
years of existence marked the end of a symbol of African airline integration.
Data from Air Transport Intelligence show that nearly 81 per cent of airlines serving
ASECNA are African. 50 per cent are from member states and 31 per cent from other
continents.
The main local carriers are Air Madagascar, Air Senegal international, Cameroon
Airlines, Air Gabon, Air Ivoire, Air Burkina, Air Mauritania, Air Togo, and Toumai Air
Tchad.
Domestic Airlines
The poor domestic markets are served by national carriers or very small companies of
which the fleet is often constituted by a single aircraft.
Regional Airlines
Air Senegal International, Bellview (Nigeria), Air Ivoire, Cameroon Airlines, Toumaï
Air Chad and Air Burkina have put in a lot of efforts to fill up the vacuum left following
the demise of Air Afrique. These airlines propose flights to travel within the region
from and to the main cities in the regions.
Chapter 2 Asecna’s Air Transport Industry
17
International Airlines
The region can be divided into two groups of countries:
1) Those that no longer have national long-haul carriers with their market largely
dominated by foreign companies.
2) Countries that still have national airlines but these are facing strong competition
from foreign companies (Cameroon, Gabon, and Madagascar).
Local Airlines
Cameroon Airline, Air Gabon, Air Madagascar and Air Senegal International are the
three main local flag carriers. They link the respective countries to Africa and mainly
Western Europe and less regularly the Middle East (During the hajj3)
Foreign Airlines
Air France-KLM is the dominant carrier on the long haul market. It serves all
ASECNA’s main airports. Swiss, SN Brussels, Iberia, Lufthansa and Alitalia also
regularly flight to the region. An important figure to highlight is the percentage of
international traffic ensured by Western airlines. In fact, according to ASECNA about
80 per cent of the commercial traffic is operated by these carriers4.
The Libyan carrier, Afriqiyah Airways is now operating to most of the defunct Air
Afrique member countries transforming Tripoli into a hub for passengers connecting to
Europe and the Middle East. Tunisia has also started flying to Bamako and Abidjan.
Royal Air Maroc (RAM) has opened routes to Dakar, Douala and Gabon.
Ethiopian, South African Airways, Kenyan Airways and Air Inter5 also have regular
connections with ASECNA.
2.3.3 Fleet
A study by Boeing showed that about 75 per cent of African fleet is composed by
regional jets or single aisle aircraft (Boeing, 2005). This does not take into account
secondary airports exclusively exploited by very small aircraft (Less than 30 seats).
3 Pilgrimage to Mecca4 Air France-KLM, TAP, Alitalia, SN Bruxels, SWISS, Iberia, Lufthansa…5 South African carrier
Chapter 2 Asecna’s Air Transport Industry
18
Most intra African routes are operated with narrow bodies, or very small jets or turbo
propellers.
Figure 2.4: Proportion of Aircraft types in Africa
Source: Afraa, 2005
41578%
9217%
245%
Jets Turbo PropellersSmall size aircraft
Chapter 2 Asecna’s Air Transport Industry
19
Figure 2.5: Intra African market Fleet (Jets + Turbo Propellers)
Source: Ambraer, 2006
New Average Old Total % of OldAfrica 162 111 316 589 54
America 1654 2581 1301 5536 24Europe 1768 1363 237 3368 7
Asia 1154 969 295 2418 12Middle East 240 144 155 539 29
Pacific 155 102 15 272 6WORLD TOTAL 5371 5529 2712 13 612 20
Table 2.2: Situation of aircraft operated in the world
Source: African Union, 2006
About 54 % of aircraft operated in Africa are considered to be old or very old. Nearly
45 % of aircraft are more than 15 years old. 20 % are between 10 and 15. 13 % are aged
between 5 and 10. Around 22 % are less than 5 years olds (figure 2.5). The average age
of the fleet is comprised between 16 and 20 years old. A large proportion of aircraft
still operated are aged over 25 and even 30. These aircraft are largely fuel inefficient.
Chapter 2 Asecna’s Air Transport Industry
20
Figure 2.6: African fleet annual utilization
Source: Ambraer, 2006
The average annual utilization is 1167 hours per aircraft. There is a strong correlation
between fleet utilization and fleet age (Coefficient of correlation equal to “- 0.8”).
0
500
1000
1500
2000
2500
3000
TP20 TP35 J35 J44 TP50 J50 TP70 J70 J80 J100 J120 J150 J175 J250 J>300
(Flights Hours per Aircraft)
0
5
10
15
20
25
30
35
40
45Fleet age (Years)
African annual fleet utilization African Fleet Average Age
Chapter 2 Asecna’s Air Transport Industry
21
Figure 2.7: African fleet Evolution from 2003 to 2023
Source: Airbus, 2005
Airbus estimates that African airlines will take delivery of about 641 new aircraft to
replace the current fleet or to sustain growth (Figure above).
2.3.4 Performance
Figure 2.8: RPK, ASK (Billion) and Passengers load factors in Africa
Source: AFRAA, 2005
Load factors, RPK and ASK are improving. But the overall industry’s health remains
critical in Africa. Load factors may look remarkably high, but they highlight the
airlines’ dilemma in the African operating climate. The problem is that break even load
factors remain higher.
0
200
400
600
2003 2023
GGrroowwtthh
SSttaayy
339922
770011
309
332
60Source: GMF 2004
664411 aaiirrccrraafftt
RReeppllaacceedd
Chapter 2 Asecna’s Air Transport Industry
22
Financial Performance
A sample of 8 airlines serving ASECNA region, comprising South African Airways,
Royal Air Maroc, Ethiopian Airlines, Kenya Airways, Air Mauritius, Bellview airways,
and Tunisair, made a net profit of over $200 million in 2005 (AFRAA, 2005, p.4).
These are encouraging and remarkable results in a world where airlines made huge
losses in the recent past But they do not reflect the real picture of the industry’s
performance. Most airlines, some very small, some bigger, are facing serious
difficulties.
Excessive debts, uncoordinated operating networks, liquidation, bankruptcy, are
examples of discrepancies generally observed (African Union, 2005). Airlines post very
poor financial results. The issue of profitability is crucial in the region: as the
market is narrow; it is difficult for local airlines to raise the necessary investment
required by the standards of modern airlines. These airlines often operate the same
routes. That competition leads to a price war resulting merely in weakening the
economic health of these companies which have difficulties in covering their operating
costs. Air Afrique6 best represents the airline industry’s situation in the area. Air
Afrique officially lost 194 million dollars between 1984 and 1996. It almost never made
significant profit. In 2002, after years of financial crisis, the 11 states that owned the
pan-African airline decided to file for bankruptcy. The Bankruptcy came after the
failure of a restructuring plan brokered by the World Bank.
The Yaoundé treaty countries have revised their national carriers by designating them
as the flag carriers. But they are left under the control of private interests, like Air
Ivoire, Air Senegal International, Toumaï Air Chad… etc. Cameroon Airlines and Air
Gabon, once the two leading carriers in the region, are now being liquidated or
privatized.
High Fuel prices
Fuel price is constantly rising. Fuel represents on average 25 per of operating costs. One
barrel costs on average 70$ world wide and up to 90$ in Africa (2005). The trend is
6 Air Afrique was established in 1961 to provide passenger and cargo service within the 12 West African Nations of Benin, Burkina Faso, Central African Republic, Cote d'Ivoire, Congo, Mali, Mauritania, Niger, Senegal, Chad, Togo & Guinea Bissau.
Chapter 2 Asecna’s Air Transport Industry
23
expected to last. These sky-rocketing fuel prices are devastating the industry. As airlines
are struggling to improve their bottom lines, fuel efficiency is critical.
Figure 2.9: Trend in Aviation fuel cost
Source: Airbus, 2005
Yields and Unit Costs
Figure 2.10: Yields and Unit costs in Key markets
0,0
2,0
4,0
6,0
8,0
10,0
12,0
14,0
Europe SouthernAfrica
Europe WesternAfrica
Within Europe North Atlantic
Yield Unit Cost Yield Cost Margin
Source: Airbus, 2005
Chapter 2 Asecna’s Air Transport Industry
24
Yields are declining and the margins remain low. The Southern Africa – Europe market
has the lowest unit cost but also the lowest yields, and the lowest margins. Europe –
Western Africa is a healthy market for efficient airlines, mainly European, with
relatively high yields. Yields are also low in the domestic market. The industry is not
expecting a significant improvement of yield.
Most African airlines are inefficient. This results into high unit costs as the figure below
shows it. These airlines possess old fleets which are highly oil-consuming. High unit
costs reflect low aircraft utilization rates, high maintenance, rental and insurance costs.
High air navigation and airport unit costs reflect their old avionics, and their low aircraft
utilization.
Figure 2.11: African Airlines 7 Operating costs (Unit cost $ per tonne per Km)
0
0,1
0,2
0,3
0,4
0,5
0,6
Fuel & Oil Flight Equipment Airport and NavigationCharges
Avg inefficient Airline Avg Efficient Airline Avg Efficient Worldwide
Source: Airbus, 2005
7 Flight Equipment comprises maintenance, insurance, and rental. The others operating expenses are not mentioned here. But it’s interesting to note that administration unit costs for non efficient airlines are extremely high, almost twenty times higher than an efficient airline’ unit costs.
Chapter 2 Asecna’s Air Transport Industry
25
2.4 Regulatory
In the absence of valid local carriers, ASECNA states have liberalized their skies
because bilateral agreements (Principle of reciprocity) are no longer functioning.
Although the deregulation process is on the way, with the ongoing implementation of
the Yamoussoukro8 liberalisation decision, the open sky agreements, civil aviation
codes are still obsolete and not harmonised. Texts on competition are not fully applied:
Current regulations impose restrictions over the number of operating airlines, and
frequency and capacity.
Western carriers want more liberalization, and would like to see the process speeded up,
as they are in a position to dominate the market further.
8 Ivory Coast, 1999
Chapter 2 Asecna’s Air Transport Industry
26
2.5 Air Travel demand
2.5.1 Traffic figures
Africa accounts for about 3% of global air traffic in term of Passenger Kilometres
performed (African Union, May 2005).
Figure 2.12: Regional share of global international scheduled air passenger traffic
Percentage share by region ( Passenger-kilometres performed in millions, 2004)
587,998 (29%)
64,326 (3 %)
785,828 (39%)
88,027 (4%)
354,353 (18%)
132,934 (7%)
Europe Latin America and CaribbeansNorth America Middle EastAsia Pacific Africa
Source: UNESCAP, 20059
This situation reflects its low income, and the lack of air transport infrastructure. This
being said, the situation of air transport in Africa is not uniform. It varies from one
region to another. Northern, Southern and Eastern Africa’s air transport performance is
good (Kenyan airways, South African, Ethiopian and Royal Air Maroc). ASECNA area
remains in a difficult situation with less traffic and unreliable structures. ASECNA’s
figures show that the region generates about 7 million passenger traffic per year (2003),
which is below what South Africa alone represents in term of annual air passengers.
9 United Nation Economic and Social Commission for Asia Pacific
Chapter 2 Asecna’s Air Transport Industry
27
Propensity to travel
Given the low level of incomes, and the widespread of poverty across the region, the
propensity to travel is very low. Moreover, the tariffs are “very high”, 20 to 30% higher
than the rest of the world according to the African Union. High air travel fares reflect
the low level of traffic, and limited load factors in most of the routes. Moreover, there
are little frequencies between city pairs. That increases aircraft operating costs.
Passenger Traffic10
Figure 2.13: Evolution of passenger traffic (1994-2003)
7,3
4,0
0,0
1,0
2,0
3,0
4,0
5,0
6,0
7,0
8,0
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
(Year)
(Millio
n P
as
se
ng
ers
)
Source: ASECNA, annual reports (1994-2003)
Passenger traffic has grown by about 75% from 1994 to 2003, increasing from about 4
million to around 7 million in 2003. This evolution is due to a sustained economic
growth on the continent and worldwide. Traffic recovery is particularly significant in
some countries. After recent political unrests in Madagascar and Congo, passenger
traffic in main airports grew respectively by 70 and 17 per cent between 2002 and 2003.
The increase of figures in the region is also driven by oil- related activities in Chad and 10 Ässengers Traffic in ASECNA main Airports
Chapter 2 Asecna’s Air Transport Industry
28
Equatorial Guinea. The construction of the pipeline between that country and the
oceanic coast through Cameroon has stimulated traffic.
Passenger Traffic by Airport
Figure 2.14: Average Airport Passenger Traffic (2000-2004)
484
500
700
787
1336
0 200 400 600 800 1000 1200 1400 1600
Niamey (Niger)
Ndjamena (Chad)
Nouakchott (Mauritania)
LOME (Togo)
Ouagadougou (Burkina)
Yaounde (Cameroon)
Cotonou (Benin)
Port Genrtil (Gabon)
Malabo (Guinea)
Bamako (Mali)
Pointe Noire (Rep Congo)
Antanarivo (Madagascar)
Brazzaville (Rep Congo)
Douala (Cameroun)
Libreville (Gabon)
Abidjan (Ivory Coast)
Dakar (Senegal)
(Thousand Passengers)
Source: ASECNA, annual reports (2000-2004)
Among the main airports, Dakar airport is the first in the region with more than 1
million passengers per year. It’s has been the fastest growing airport in term of
passenger volume. The important tourism activity in Senegal is the major factor that
explains this performance. The traffic is globally increasing in other airports.
Secondary airports in ASECNA receive insignificant passenger traffic and are often
served by very small aircraft.
Chapter 2 Asecna’s Air Transport Industry
29
Domestic passenger traffic
Domestic markets are particularly poorly developed across the region. People tend to
travel by road or rail despite the poor state of the network. Only the elite, and business
men who can afford it, use air travel to move within countries. Only Gabon has a
relatively developed domestic market with more than 340,000 passengers in 2003
(Bergonzi, 2006, P7).
Regional passenger traffic
While regional traffic has significantly increased within the other African regions, it has
stagnated in West and Central Africa from 1994 to 2001.
Political trips, seminars, regional emigration and business travels are the main drivers of
regional traffic. However, the mobility from one country to another remains extremely
difficult. It’s sometimes easier to reach another country within the region through Paris
for instance. On the 276 regional city pairs, only 5 per cent of them have 150 passengers
per day (table below). The busiest city-pair is Abidjan – Dakar.
Daily passenger Number of
city pairs
Percentage (%)
More than 150 14 5
70 - 150 28 10
30 - 70 69 25
10 – 30 69 25
Less than 10 96 35
Table 2.3: Daily passenger traffic between city pairs.
Source: Délia Bergonzi, 2006
The most frequent connections in ASECNA are: Dakar-Bamako, Dakar-Abidjan,
Bamako-Abidjan, Douala-Libreville, and Cotonou - Pointe Noire. They all have more
then 100,000 passengers per year. Dakar and Abidjan are the two destinations with the
highest regional passenger traffic, performing respectively 350000 and 200000
passengers per year (OEDC, 2005). Dakar has 15 direct links with others regional cities
and Abidjan is directly linked to 12 others West African cities. The heaviest traffic
flows are the Gulf of Guinea (Abidjan-Accra-Lagos corridor), then the Dakar/Abidjan
axis.
Chapter 2 Asecna’s Air Transport Industry
30
The lack of air links in the Central and Western regions is at a damaging situation with
the presence of a number of landlocked states (e.g. Congo, Central African Republic,
Chad, Mali, Niger), where aviation is needed most.
International Passenger traffic
Almost 50% of passenger traffic (6 million out of 11 in 2003) in western and central
Africa is international. Traffic at major airports in ASECNA is presented in table
below.
2000 2001 2002 2003
Dakar 803.8 863.2 918.3 1005.6
Abidjan 744.6 6448 301.9 3127
Douala 198.8 252.9 246 283.5
Bamako 168.2 132.2 112.1 197.1
Antananarivo 198.2 209.9 98.5 176.1
Libreville 246.4 203.9 198.9 149.6
Malabo 42 64 73,9 100.2
Table 2.4: International traffic at major regional airports (Thousand).
Source: ASECNA
In international traffic, for the West and Central Africa region, and particularly in
ASECNA, the dominant connection is towards Europe.
This traffic can be divided in 3 groups: The ethnic Passenger Group, who has ties with
the former European colonial powers, France mainly, creates a natural emigration of
workers in both directions (South-North, North-South). The Leisure and Tourism
group, concerns high-income people who travel to Europe, America or Asia for reasons
such as shopping, Visits to family and friends. The Business travellers, because of
economic ties with Europe, and oil companies are also important drivers for air traffic
in the region. A large part of the traffic is also due to governmental, non-governmental
and international bodies’ staff.
Traffic towards the Middle East is increasing, mostly due to the attraction of Dubai and
pilgrimage to Mecca. North Africa / West and Central Africa traffic is also increasing
Chapter 2 Asecna’s Air Transport Industry
31
due to the dynamism of Maghrebian airlines, which take a large share of the 6th
freedom11 traffic departing from Paris to ASECNA.
There is also a significant traffic between African sub regions and ASECNA, mainly
towards South Africa. Traffic towards the United States of America is carried out
essentially via Europe.
Cargo Traffic
Figure 2.15: Evolution of Cargo traffic (1994-2003)
134
98
0
20
40
60
80
100
120
140
160
180
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
(Year)
(Th
ou
san
d T
on
ne
s)
Source: ASECNA, annual reports (1994-2003)
Freight traffic has regularly increased from 1994 to 2000 due to economic upturn. The
decrease observed since 2001 is explained by a dramatic reduction of cargo traffic at
11The right to carry passengers or cargo from a second country to a third country by stopping in one's
own country.
Chapter 2 Asecna’s Air Transport Industry
32
main cargo airports (Pointe Noire and Brazzaville in the republic of Congo). But overall
cargo traffic has increased by nearly 37 per cent since 1994.
2.6 Conclusion
The aim of this chapter was to introduce to ASECNA’s air transport industry, and to
find out its main characteristics. This is what was found.
1. ASECNA region is characterised by under development and extreme poverty
2. Air Transport infrastructure is in a bad state or is largely insufficient and the
substitutes to air transport are poorly developed.
3. The airline industry is very weak, and mostly composed of small aircraft
a. Local companies are facing economic and financial difficulties
b. Operating costs are hit by soaring fuel costs, and low aircraft utilisation
c. Yields and margins are low on the domestic market
d. Most local airlines are very small and very often inefficient
e. The fleets are very old
f. The long haul and medium haul markets are dominated by foreign carriers
g. The domestic market is insignificant
4. Air travel is still constrained
a. On the demand side by low incomes
b. On the supply side by regulations
5. Some changes are being observed
a. Aircraft manufacturers expect a fleet renewal over the next years
b. Liberalization policies are slowly being adopted on the basis of the
Yamoussoukro decision
c. New entrants are expected, even low cost carriers
What do these characteristics mean for air navigation service provision and for
ASECNA?
The poor development of air transport substitutes means air transport is crucial to
ASECNA region and should be among the priorities. In order to develop safely and
orderly, the region’s air transport industry needs a reliable air navigation infrastructure
and an adapted air navigation service provision. Air transport cannot develop without
these conditions.
Chapter 2 Asecna’s Air Transport Industry
33
Airlines facing difficulties need to improve their efficiency to mitigate the effects of
high fuel costs. With the very low level of yields on the domestic markets and on some
international routes, and given the ultra competitive environment in a limited number of
profitable routes in ASECNA, it is unlikely that there is significant scope for a recovery
in the yields in the next years. Airlines are going to renew their assaults on costs
according to African Airlines Association (AFRAA). These include flying the shortest
routes, carrying optimum of fuel, cruising at optimum speed, minimizing flights at low
altitude during descend and climb. Therefore ASECNA must deliver enough capacity
and airspace flexibility to its customers
But efficiency also means that ASECNA must deliver a cost effective service
provision.
These airlines’ fleets are often very old. Ageing fleet means they are unable to cope
with technological advancements and automation of security and safety systems.
However the fleet renewal expected by manufacturers means higher speeds, and
increased speed variability in ASECNA’s airspace.
The predominance of foreign carriers in ASECNA means the agency must pay attention
to their requirements as well as those of local airlines.
The liberalisation process and the growth of economies in the region will have a
positive impact on competition and on air travel. ASECNA must anticipate these
mutations, and their foreseeable impact on the air navigation system, and articulate its
strategy to match the other exigencies mentioned above.
34
Chapter 3 : Air Navigation Performance review
The aim of this chapter is to analyse the performance of ASECNA’s air navigation
system, and to find out the current system’s shortcomings. Figure 3.1 shows the
region’s Flight Information Regions (FIRs).
3.1 Introduction
The agency controls an area 1.5 times as large as Europe. The region is characterised by
the presence of large inhospitable areas: Oceans, Deserts, and Forests.
The area is divided into 6 Flight Information Regions (FIRs): Antananarivo,
Brazzaville, Dakar Oceanic, Dakar Terrestrial, Niamey, and N’Djamena1. The airspace
is divided into lower and upper zones. The FIRs encompass Terminal Control Areas
(TMAs) or Upper Control Areas (UTAs) as required by ICAO.
ASECNA ensures the control of air navigation flows, aircraft guidance, the transmission
of technical and traffic messages, airborne information. ASECNA delivers terminal
approach aids for the region’s 25 main airports2, as well as for 76 secondary airports.
This includes approach control, ground aircraft guidance and movements, radio aids,
and fire protection services. The agency also gathers data, forecasts, and it transmits
aviation weather information. Theses services are delivered for en route, terminal
approach and landing phases of flights.
3.2 Airspace organization
3.2.1 Description of ASECNA’s FIRs
Dakar’s FIRs
They are located in western Africa. A large part is constituted of inhospitable desert
areas. It is composed of two parts: oceanic and continental. The area is
1 These cities are respectively the capitals of the following countries: Madagascar, Congo, Senegal, Niger and Chad. The Senegalese FIR is divided into an Oceanic FIR and a terrestrial FIR. 2
Douala, Port Gentil, Mahajanga, Garoua, Malabo, Bamako, Bangui, Ouagadougou, Gao, Brazzaville, Bobo-Diolasso, Niamey, Pointe Noire, Nouakchottt, Dakar, Abidjan, Nouadhibou, N’djamena, Cotonou, Toamasina, Sarh, Libreville, Ivato, Lome.
Chapter 3 Air Navigation Performance review
35
classified Class G and F3 and D airspaces. The lower limit is flight level 245 (FL
245). There are about two dozens Prohibited, restricted and dangerous (P.D.R) zones in
the area. The situation is critical above Ivory Coast where three large PDRs areas are
located next to Abidjan’s TMA.
Dakar’s FIRs are bordered by the Following FIRs: Atlantico SBAO, SAL, Canaries,
Alger, Accra (Ghana) and Niamey (Niger). Sierra Leone, Guinea and Liberia manage
Roberts’ FIR, which is a dismemberment of Dakar’s FIR.
There are one Area Control Centre (ACC) in Dakar and one Flight Information
Centre (FIC) in Abidjan.
N’djamena’s FIR
It covers Chad and partly Cameroon, CAR, and Niger. The Airspace is classified G. The
FIR is bordered by Khartoum’s FIR in Sudan, Kano’s FIR in Nigeria, and Tripoli’s FIR
in Libya. One ACC manages the airspace.
Niamey’s FIR
It is located in Western Africa and largely covers an inhospitable desert area. The
airspace is classified class G. The lateral and vertical limits are equivalent to those of
Dakar’s FIR. The FIR divided in two parts: East and West. It is bordered by Kano in
Nigeria, Alger, Khartoum in Sudan, Tripoli in Libya and N’Djamena in Chad. One
Flight Information Centre controls the airspace.
Brazzaville’s FIR
Brazzaville’s FIR (Congo) occupies a central position, between eastern southern and
western Africa. The land below the airspace is an inhospitable virgin forest. The lower
limit is FL 245. The Bordering FIRs are Kano, N’djamena; Kinshasa and Kisangani in
Democratic Republic of Congo (DRC), Khartoum, and Luanda in Angola. One FIC
manages the airspace.
3 Typically Class F Advisory airspace is designated where activities such as gliding, parachuting, high traffic training areas, and military operations take place and it would be of benefit to aircraft operators to be aware that such activities are taking place there.
Chapter 3 Air Navigation Performance review
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Antananarivo’s FIR
Antananarivo’s FIR is in the trans-Indian ocean area, interfacing with the Asia pacific
region, where there is high density traffic. The airspace is classified G, and the
horizontal limit is FL 245. The Neighbouring FIRs are Maurice, Seychelles, Durban in
South Africa, and Beira in Mozambique. One FIC manages the region.
3.2.2 Fragmentation
FIRs in ASECNA do not strictly follow the contours of national boundaries, and the
delimitation of these FIRs is generally in line with operational requirements.
Brazzaville’s FIR for example regroups partly or entirely 5 countries: Cameroon,
Congo, Equatorial Guinea, Gabon and a part of the Central African Republic (CAR).
N’djamena’s FIR regroups Northern Cameroon, Chad, Northern CAR, and Eastern
Niger. Niamey’s FIR is composed of Niger’s airspace, Eastern Mali, and Burkina.
However, the neighbouring airspaces are managed by different countries: as said earlier,
Sierra Leone, Guinea, and Liberia jointly control their airspaces. Ghana manages its
airspace and that of Benin, Sao Tome and Principe and Togo from Accra’s FIR. Cape
Verde has an extensive oceanic airspace called Sal FIR. Nigeria’s national airspace is
composed of two FIRs: Kano in the North and Lagos in the South. Algeria, Morocco,
Libya, Sudan, the DRC and South Africa also manage their own airspace separately.
Aircraft that fly from one airspace to another have to switch to the local frequency.
This goes along side with varying requirements and procedures from region to region,
and proliferation of ATC systems and technologies according to national and regional
considerations.
That fragmentation is an important cause of inefficiency, in term of cost-effectiveness
and productivity. It contributes to the multiplication of fixed assets and costs, as well as
to higher coordination and transaction costs:
1. Duplication of Air Navigation Service Providers
2. Duplication of Air Traffic Service Units (Area Control Centres, Approach Control
Units)
3. Duplication of ATM Systems and Interfaces
4. Duplication of CNS infrastructure
5. Multiplication of Regulators
Chapter 3 Air Navigation Performance review
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Figure 3.1: ASECNA’S FIRs
Chapter 3 Air Navigation Performance review
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3.3 TrafficFigure 3.2: Number of flights from 1993 to 2003
218 209
354 774
0
50 000
100 000
150 000
200 000
250 000
300 000
350 000
400 000
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
(Year)
(Nu
mb
er o
f M
ovem
ents
)
Source: ASECNA, annual reports (1994 - 2003)
As defined by ICAO, air traffic is the number of aircraft flights operated in a given
airspace. In 2003, more than 354774 flights were operated in ASECNA, which
represents a 63 per cent increase comparing to 1993. This represents 646 aircraft
movements every day. The growth has been constant, at an average yearly rate of
5.3 per cent (Figure 3.2).
3.3.1 Airport Activity
During the last ten years, traffic in the region’s airports has continuously grown. The
number of aircraft movements has increased by 5.3 per cent per year on average. In
2003, international and local airlines’ activity4 has increased, mainly driven by a
noticeable economic recovery in the region, with a 3.1 per cent average growth
(ASECNA, 2003) and between 4 and 5 per cent in 2004.
4 Air Madagascar, Air Senegal International, Air Mauritanie, Nouvelle Air Ivoire, Air France, Air Burkina SA, Societe de Transport Aerien Malien, National Airways Gabon, UTAGE, Afriqyah Airways, Afric Aviation, Air Excellence, West African Airlines.
Chapter 3 Air Navigation Performance review
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Figure 3.3: Number of aircraft movements at 15 key airports
Source ASECNA, annual report (2003)
Libreville is the busiest airport in the region in term of movements as Figure 3.3 shows
it. Dakar and Douala are respectively second and third.
Runway Capacity
Runway capacity is often the limiting factor for airport capacity. The queuing theory
indicates that smoother arrival flows allow increased throughput and reduced delay. It
allows the trade off between capacity and delay to be improved. To maximise the use of
runway capacity, it is essential to accurately guide aircraft at the final approach fix
(FAF).
There were about 18.66 aircraft movements per hour in ASECNA’s airports from
2000 to 2003. Libreville’s airport had 3.37 movements per hour, followed by Dakar and
Douala, respectively 1.99 and 1.95. Six international airports had less than one
movement per hour. Of course, these average figures do not take into account the
variation of traffic. However, even during busy periods, the busiest platforms, like
Libreville or Dakar hardly reach 9 movements per hour. The runway occupancy remains
at very low levels. This clearly indicates that runway capacity is not an issue of
concern in the region as it is in European or North American airports.
Chapter 3 Air Navigation Performance review
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3.3.2 En route Traffic
The main Airstreams
The statistics from 2001 to 2003 indicate that the segmentation of en route traffic is
stable, and is mainly composed of intra Africa activities, and flows between Africa and
European countries (Table 3.1).
The heaviest traffic flows are the Gulf of Guinea (Abidjan-Accra-Lagos corridor),
followed by the Dakar/Abidjan axis and the North-South traffic flow. The East-West
traffic is less dense. The traffic between European countries and the region which
represents 25 per cent of all activities is driven by Air France-KLM. The activity is less
important towards other parts of the world: Traffic towards the middle is low.
Exchanges with America are relatively poor. However, routes between that part of the
world and Europe go through ASECNA’s FIRs (Figure 3.4).
1999 2000 2001 2002 2003
Intra-Africa 175693 199172 224374 225398 236812
Europe-Africa 80628 82568 80492 78081 84690
Europe-America 21012 22257 23651 22175 21843
Middle east-Africa 3579 3927 3982 4609 4838
America-Africa 3748 4266 4894 4460 4788
Divers 23368 2565 2671 2969 1803
Total 287008 314755 340064 337692 354774
Table 3.1: The main Airstreams in ASECNA
2001 2002 2003 Average
Antananarivo 35893 28157 35086 33045
Abidjan SIV 24339 23312 26861 24837
Niamey 31825 32694 34703 33074
N’Djamena 23030 24588 25747 24455
Brazzaville 59987 62385 63811 62061
Dakar 57887 57725 58889 58167
Table 3.2: Traffic by FIR
Chapter 3 Air Navigation Performance review
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Figure 3.4: Areas of Routing.
Source: ATNS
In Dakar’s FIRs, major traffic flows are driven by airstreams from the Americas and
Europe. The FIRS are involved in air activities between Europe and South America, and
in the Atlantic Ocean interface between the North Atlantic, Africa, and South America
regions. Input traffic also comes from the Coastal routes over the Gulf of Guinea and
from Trans-Sahelian operations (Figure 3.4). Dakar’s FIRs accounted for about 25 per
cent of all ASECNA’s traffic on average from 2001 to 2003.
Niamey’s FIR is mainly involved in Trans-Saharan traffic flow and Europe to southern
Africa routes. These routes receive an important traffic due to the activity generated by
South Africa mainly. Fourteen per cent of the traffic went through Niamey during the
period considered.
N’djamena’s FIR’s activity is mainly constituted of over flights from southern, eastern
and central Africa. The area accounted for about 10 per cent of activities during the
period. Traffic density is low.
FIRs Niamey & N’Djamena
FIR Brazzaville
FIR Dakar
Chapter 3 Air Navigation Performance review
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Brazzaville accounted for 27 per cent of flights during the period. A large part of traffic
in Brazzaville’s FIR comes from South Africa.
En route Capacity5
Flights
per Day
Flights
per Hour
Percentage
(%)
Number
of ATCO6
Traffic Density
Dakar 159 6.6 24 42 Low
N’Djamena 67 2.8 10 40 Low
Niamey 91 3.8 14 33 Low
Brazzaville 170 7.1 27 23 Low
Antananarivo 91 3.8 14.5 27 Low
Abidjan 68 2.8 10.5 26 Low
ASECNA 646 26.9 100 391 Low
Eurocontrol 22920 955 100 NA Very High
Table 3.3: Average traffic density from 2001 to 2003
Sources: ASECNA, internal document (appendix 10), and annual reports (2001-2003). Eurocontrol, Performance Review Reports (2001-2004)
Dakar’s ACC and Abidjan’s FIC manage on average 227 flights per day, which is
equivalent to 9.4 movements per Hour and 1 movement every 7 minutes. But this does
not take into account the time and period distribution of flights.
Brazzaville is the second busiest FIR as the FIC manages about 170 flights per day,
which represents 7.1 movements per hour and one every nine minutes.
About 67 flights are managed by N’djamena’s ACC each day, representing 2.8 flights
per hour and about one flight every 21 minutes,
In Antananarivo, on average, 91 aircraft movements are managed every day, 3.8 flights
per hour, and 1 every 17 minutes.
Traffic density in ASECNA is very low when compared to the level of traffic in
Europe.
5 The average number of flight per day and per are obtained by dividing the number of flights per year by 365. 6 Air Traffic Controllers (2004 figures).
Chapter 3 Air Navigation Performance review
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Controllers’ Productivity
Productivity is defined as the average number of aircraft controlled per hour per air
Traffic Controller (ATCO). It is calculated by dividing the total number of aircraft
movements in the FIRs by the total number of ATCOs. A better way to measure
productivity would have been to measure the number of flight-hours controlled per
controller-hour in duty, but the data were not available. Eurocontrol’s figure is derived
from the average flight-hours controlled per ATCO-Hour in duty, and annual number of
IFR flights and the number of flight-hours. The average flight-hours controlled per
controller-hour in duty was 0.8 (Eurocontrol). There were 12.2 million flight-hours and
8.9 million IFR flights in Europe in 2004. This means 1.37 Hours per flight on average.
Therefore, each controller controls 0.8 divided by 1.37 (0.583) flight per hour.
Figure 3.5: Average flights controlled per hour and per controller in ACCs
ATCOs’ productivity in ASECNA varies from one ACC to another. The busiest ATCOs
are those of Dakar and Brazzaville. Each air traffic controller controls on average 0.1
flight per hour in ASECNA, whereas the equivalent figure is about 0.6, which is 6 times
higher.
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Antana
nariv
o
Abidjan
SIV
Niamey
N’Djam
ena
Brazza
ville
Dakar
ASECNA
Euroc
ontro
l
(Control Centres)
Chapter 3 Air Navigation Performance review
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3.4 Delays
Air transport delays are given by the scheduled departure and arrival times. Delays can
be broken down by phase of flight.
When traffic demand is anticipated to be higher than the actual ATM capacity in en-
route control centers, or at the airports, Air Traffic Units may apply Air traffic Flow
Management (ATFM) regulations. This means that airplanes subject to that regulation
are held at departure airports. The AFTM delay is then allocated to the busiest ATC
unit.
In ASECNA, delays are almost never the result of Air traffic services. Except during bad
weather periods, the totality of delays is due to airlines’ preflight operations. There is no
ATFM unit like in Europe for instance (Ngoué Celestin, Head of Air Navigation,
ASECNA). Many airlines managers confirmed that reality, which is also corroborated
by the availability of sufficient airspace capacity.
3.5 Impact of future trends
3.5.1 Prospects
All aircraft manufacturers (Boeing, Airbus...) or airlines organisations (IATA, ICAO)
use roughly the same methodology for assessing long term traffic forecast. It is based on
the assumption that long-term demand for air travel is driven by economic
developments, notably the growth of world and regional income levels.
Chapter 3 Air Navigation Performance review
45
Figure 3.6: Projected traffic growth over the next decade
4
4,2
4,4
4,6
4,8
5
5,2
Africa
- PR
C
Africa
- M
iddle Eas
t
Africa
- USA
Africa
- W
este
rn E
urop
e
Africa
- Can
ada
Africa
- Ja
pan
Africa
- CIS
Africa
- Sou
th A
mer
ica
Africa
- Aus
tralia
/NZ
Africa
- Eas
tern
Eur
ope
Per
cent
age
Source: Boeing, Airbus, ASECNA, IATA.
Western and Central Africa countries economies are expected to grow at an average
pace of 4.5 per cent during the next decade according to African bank of development
(BAD). It can be assumed that air travel and air traffic are going to follow that pace.
Depending on the industry’s estimate taken into account, air traffic will grow in Africa
between 5 and 7 per cent over the next 15 years. ASECNA expects even a 7 per cent
growth. However, Africa’s overall share of traffic is expected to decrease to 2 per cent
instead of the current of 3 per cent.
The average growth rate for the next 15 years is 5 per cent yearly. This means there will
be about 737550 flights in ASECNA by 2020; traffic will have doubled.
3.5.2 Impact on Runway Capacity
With the projected growth rate, there would be about 41 landings or take-off each hour
in all ASECNA area airports. If the relative importance between airports does not
change, Libreville will handle around 7 movements per hour followed by Dakar and
Douala with respectively with 4.7 and 4.3 operations per hour on average (Figure 3.7).
Chapter 3 Air Navigation Performance review
46
Comparatively, the busiest hour at London Heathrow in 1999 saw 93 movements per
hour on the airport's two runways.
Figure 3.7: Projected Runway Occupancy in main airports (flights per hour)
0
1
2
3
4
5
6
7
8
Librev
ille
Dakar
Douala
Mala
bo
Abidja
n
Port G
entil
Bamak
o
Antana
nariv
o
Coton
ouLom
é
Nouak
chott
Ouaga
doug
ou
Niamey
Toam
asina
N'djam
ena
Source: ASECNA, compiled from annual report 2003.
3.5.3 Impact on en route Capacity
Flights per
Day
Flights Per
Hour
Percentage
of Total
Number of
ATCOs
Traffic
Density
Dakar 332 13.8 24 104 Low
N’djamena 140 5.8 10 60 Low
Niamey 189 7.9 14 76 Low
Brazzaville 354 14.7 27 76 Low
Antananarivo 189 7.8 14.5 72 Low
Abidjan 141 5.9 10.5 35 Low
ASECNA 1343 56 100 699 Low
Table 3.4: Average traffic density by 2015
Chapter 3 Air Navigation Performance review
47
ASECNA’s FIRs would receive about 1342 flights per day (56 per hour). It is
insignificant when compared to Europe’s records, 30,000 flights per day, and one
operation handled every 3 seconds (CFMU, 2005).
Controllers’ productivity
Figure 3.8: Projected Controllers’ productivity in 2015
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Antana
nariv
o
Abidjan
SIV
Niamey
N’Djam
ena
Brazza
ville
Dakar
ASECNA
Controllers’ productivity would remain lower than European controllers’ 2003 record.
3.6 Traffic complexity
A good analysis would require additional data such as flow structure (horizontal
intersection per miles), traffic mix (standard deviation of aircraft speed), and traffic
evolution (number of flight level changes per miles, horizontal intersection per miles).
These information were not available. However, traffic density is low and will remain
so in ASECNA. All the busiest routes are north and south bound. These routes generate
the highest levels of passenger traffic. They link major local airports to Europe.
Domestic traffic is inexistent and East-West routes are not really busy, except the golf
of Guinea corridor, and routes between certain capital cities. But,
Chapter 3 Air Navigation Performance review
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seasonally, during the pilgrimage period, routes towards Saudi Arabia (East-West)
cross major North-South traffic flows, and create convergent points generating traffic
complexity (Samake Wodiaba, ASECNA). The projected growth suggests that traffic
complexity is going to increase as east-west flows are going to grow faster than north-
south operations.
3.7 Safety
Safety is the prime objective of ATM. In ASECNA’s safety reports, events are
composed of 6 elements: Air proximities (Airprox), users’ claims, Aviation security,
Bird strikes and Accidents. The period considered goes from 1999 to 2004. 2004
figures in the chart below are only partial data.
3.7.1 Air Proximities
An airprox is a situation in which, in the opinion of a pilot or a controller, the distance
between aircraft as well as their relative positions and speed have been such that the
safety of the aircraft involved was or may have been compromised. The number of Air
proximities is constantly high with regard to the low traffic density in ASECNA.
Figure 3.9: Evolution of Air proximities
0
5
10
15
20
25
30
250 275 300 325 350
Number of flights (000)
Air
pro
xim
ities
Source: ASECNA, annual reports (1999-2003)
Chapter 3 Air Navigation Performance review
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The situation seems to improve with the increase of traffic (Correlation between the
number of air proximities and traffic figures is equal to “-0.8”). This may reflect a better
surveillance and communication capability in the region. The number of safety-related
events seems to vary significantly between ASECNA’s regions. Central Africa
concentrated 50% of total events during the year 2004. It is not clear whether or not this
is due to differences in reporting practices, or the concentration of traffic on certain
corridors not properly furnished with surveillance means.
Figure 3.10: Evolution of incidents during the last six years
Source: ASECNA, (unpublished document).
3.7.2 Users’ claims
Users’ claims accounted for about 20 per cent of reported events. These are made by
airspace users. ASECNA statistics do not tell if every claim is investigated. It’s likely
that many are purely ignored, due to the lack of mean to conduct an efficient
investigation.
3.7.3 Birdstrikes
Birdstrikes are very frequent in ASECNA. 28 per cent of incidents during the period
were related to aircraft engines “swallowing” birds, very often at the vicinity of airports.
Chapter 3 Air Navigation Performance review
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Accidents reported are not always related to air navigation events. They nearly
constitute 26 per cent of events. Most of them occur on the ground, at major or
secondary airports (runway incursions). The figures presented on Figure 3.10 are
probably optimistic as many accidents or incidents are not reported at all, particularly at
remote airports.
3.7.4 Safety Review System
Four features are essentials to make incident reporting useful for accident prevention
and safety management:
1 A reliable, timely and large enough information flow
2 Data analysis
3 Severity Classification
4 Exposure of the data
For every incident assessed ASECNA determines one or more causal factors. These tell
the agency why events started in each instance and signposts the lessons to emerge.
ASECNA has safety committees that perform that job. It is self evident that attention
paid to the cause of an accident is worthwhile because it is likely to deliver and promote
better prevention and to establish the responsibilities. ASECNA is often responsible for
safety related events. But the agency does not seem to systematically investigate
incidents, and information on safety data is hardly available. When it is, it’s not
adequately classified.
3.8 Efficiency
3.8.1 Flight efficiency
Flight efficiency is the next key performance Area considered in this study. Flight
efficiency has implications for fuel burn, pollution and its environmental impact. Flight
efficiency has horizontal and vertical components, which can be split into en-route and
terminal flight phases. The report focuses on en-route flights. Insufficient information is
currently available to address vertical flights efficiency. Moreover, it has not been
Chapter 3 Air Navigation Performance review
51
possible to study the most “constraining points7” in ASECNA.The safest routes in
ASECNA are controlled routes. These routes are equipped with ground based
navigation aids pilots have to follow. That compulsory process increases routes length
and reduces flight efficiency. Major routes link South Africa to Western Europe.
Aircraft have to go through Brazzaville, Niamey or N’Djamena. To go from Douala
(DLA, Cameroon) to Dakar (DKR, Senegal), pilots have to use the following routes:
1. UB 737 from Douala to Sao Tome and Principe (TMS)
2. UA 400 from Principe to Abidjan (ABJ)
3. UR 979 from Abidjan to Dakar, or UB 600 through Monrovia (Liberia) and
Conakry (Bissau) (Figure 3.11).
Figure 3.11: Flight Paths between Douala and Dakar.
(In Red: Direct path. In dash Blue: Conventional path)
3.8.2 Fuel Efficiency
The fuel efficiency of an airline is determined by many factors. Some are directly under
airlines control, others are not. The later are related to market, technology, and
infrastructure.
7 The most constraining point is the point along a trajectory that contributes the most to the additional distance. This point generates additional costs.
Chapter 3 Air Navigation Performance review
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Figure 3.12: The different phases of a flight
Source: Mitre Corporation
To illustrate this requirement of fuel efficiency, the following is an estimation of extra
costs related to flight inefficiency on the route Douala (DLA) - Dakar (DKR). Only the
cruise portion of the flight is considered.
The aircraft operated is a B737-3008. Its seat capacity is 140 and range is 4320 Km. The
range is chosen such that the effect of load factor that have an influence when the
aircraft is operated at the limits of range can be neglected. The fuel consumption for a
B737-300 is estimated at 26 g/seat.km (Japan Airlines, 2005). Most of the aircraft
weight is then considered to be fuel and hull. We assume that the flight altitude on the
cruise portion is 32800 feet, and the weather condition are ideal, and the traffic is not
complex and does not generate holding patterns.
The cruise speed is supposed to be constant at 815 km/h. The descent starts about 100
km from each airport. The Descent phases of flight (Vertical profile) and the taxi times
are not considered, although we already know that efficient approach operations allow
fuel saving. The Fuel Density is 800g/litre; and the current spot fuel cost around the
world is about US$1.80 / US gallons.
8 Details from (Air Charter International, 2005)
Chapter 3 Air Navigation Performance review
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Conventional Flight (Following ground Navigation aids)
Distance Flown during the horizontal profile: 3640 Km – 2*1009 = 3440 Km
Seat.Km: 512560
Fuel Burn: 13327 Kg, which is equivalent to 16659 litres, and 4401 US gallons10
Fuel cost: 7922 US$
Direct Flight
Distance Flown during the horizontal profile: 3211 Km – 2*100 = 3011 Km
Seat.Km: 448639
Fuel Burn: 11665 Kg, which is equivalent to 14582 litres, and 3853 US gallons
Fuel cost: 6936 US$
Comments
The difference in term of Fuel consumption is about 2077 litres, 12.5 per cent. The
savings on the horizontal profile only would be about 986 US$. For 6 legs per week, the
total reduction in fuel cost is 5916 US$. Assuming continuous operations without
disruptions during the whole year, the savings would be 307,632 US$ on that single
route. But a large part of fuel inefficiency also lies on the problem of aircraft age. Old
aircraft generally consume more fuel than newly built ones as shown in chapter 2.
Flying the direct route would also free 164 hours during the year that a company could
use to improve aircraft utilization. But this would depend on the slot structure at the
served airports.
Beyond the improved aircraft economics, the positive impact on environment is also
substantial. On this case, the reduction in Carbon Dioxide (CO2) emission would be
about 1815 tonnes11 during the year.
9 We assume that that the descent phase begins 100 Km before the airport10 1 USGAL = 3.785412 Litres11 1 Kg of fuel burn produces 3.5 Kg of CO2 (Japan Airlines, )
Chapter 3 Air Navigation Performance review
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3.9 Cost effectiveness
3.9.1 Navigation charges
Figure 3.13: Evolution of Air Navigation charges (Unit Rate) in ASECNA (Euros)
0
20
40
60
80
100
120
1999 2000 2001 2004 2005 2006
DOMESTIC FLIGHTS REGIONAL FLIGHTS
INTERNATIONAL FLIGHTS
Source: ASECNA
ASECNA’s current charging policy is as follows: Charge for use of en-route facilities
and services managed by the agency are payable whatever are the conditions in which
the flight is accomplished (IFR or VFR) and whatever are the departure and the
destination aerodrome. Charging varies depending on the nature of the flight (national,
regional, international). For regional or domestic flights, users pay a fixed price. For
international flights, users pay a price that varies with the weight of the aircraft and the
distance flown.
From 1999 to 2005, charges for international flights increased by 40 per cent. But, the
price is stabilized since 2004 thanks to an agreement with IATA. The price of regional
flights is being reduced since 2001, and the price of domestic flights is stable.
Chapter 3 Air Navigation Performance review
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3.9.2 Air Navigation Services Costs
Evolution of Costs12
Figure 3.14: Personnel, ANS and Transport costs from 1996 to 2003
0%
10%
20%30%40%
50%60%
70%80%
90%100%
1996 1997 1998 1999 2002 2003
Costs of Personnel Cost of ANS Other Costs Cost of Transport
Source: ASECNA, annual reports (1996 – 2003)
The costs of personnel represent more half of total costs. They have increased
continuously since 1996. ANS and personnel costs accounted for about 80 per cent of
expenses in 2003, and their share is stable. Transports costs are stable.
12 ANS costs include supplies and materials. ANS personnel costs are included in personnel costs
Chapter 3 Air Navigation Performance review
56
Figure 3.15: Evolution of the average cost per flight from 1996 to 2003 (Euros)
220
230
240
250
260
270
280
290
300
1996 1997 1998 1999 2002 2003
Source: Compiled from ASECNA’s annual reports (1996 – 2003)
The average unit cost is increasing. The cost per flight was about 288 Euros in 2003.
Unit cost has increased by 18 per cent on average from 1998 to 2003, which represents
an annual increase of 3.6 per cent. On average, ASECNA’s unit cost is the lowest as
shown on the table below. But that figure does not reflect the exact reality, as domestic
and regional airlines only paid a fixed price, whereas international flights are much
more expensive. It means international airlines pay a much higher unit cost per flight.
Nearly 80 per cent of these charges are paid by major western and international
airlines (ASECNA, 2003).
ASECNA 28813
Eurocontrol 591
FAA 35114
Table 3.5: Average ANS cost per flight (Euros)
in Europe ASECNA and the USA (2003)
The totality of charges above is passed to users. En route revenues have continuously
increased since 1996 by 11.6 per cent on average per year (Figure 3.16)
13 ASECNA’s figure includes all personnel costs. ANS personnel costs were not available separately14 357 dollars
Trend Line
Chapter 3 Air Navigation Performance review
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Figure 3.16: Evolution of En route revenues from 1996 to 2003 (Million Euros)
020406080
100120140160180
1996 1997 1998 1999 2002 2003
Source: ASECNA, annual reports (1996 – 2003)
3.10 Cooperation
ASECNA cannot deliver a satisfactory service without interacting with other air
navigation authorities in the region. The agency encircles large blocks of airspaces like
Nigeria, and Ghana as described in chapter 2. It also shares common airspace borders
with huge entities such as the Canaries, SADC, Algeria, Libya, Sudan and others.
Nigeria has deep infrastructural deficiencies, which gave rise to the blacklisting of their
airspace by some international organizations: Obsolete navigation and landing aids as
well a collapsed surveillance system. The navigation and landing aids are not
functional most of the time, the six terminal approach radar stations are broken down
and air traffic control service are not provided to some en-route traffic (Nigeria
Airspace Management, 2005).
Chapter 3 Air Navigation Performance review
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Figure 3.17: Regional Fragmentation of ATM sectors
Source: CANSO
Clearly cooperation is needed between all these states to develop a seamless and cost
efficient ATM system at a regional level. Harmonisation provides much of the answer.
The region needs a plan to achieve common standards procedures and technology, and
ensure interoperability between various systems. Multi-national cooperation among
provider States and users are essential to minimize investment costs, ensure
compatibility and avoid duplication of effort. Moreover, by agreeing on common
technologies, ANSPs and state would increase their bargaining power when buying new
systems.
Trans-national bodies provide coordination (ICAO’s AFI CNS/ATM regional Sub-
Groups). But still, there are challenges in bringing the regulators and the governments to
commit to an efficient air navigation system. African states, airspace users, ATC service
providers, and equipments suppliers do not have the same motivations and benefits.
Moreover, “different regulatory models, different regulatory requirements undermine
moves towards harmonisation. Sovereignty issues, slowness in administrative and
legislations procedures, differences in time frames, often contribute to delay advances
in the system” (Yoro Amadou Diallo, ASECNA).
Chapter 3 Air Navigation Performance review
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3.11 Training
Traffic is growing and complexity is increasing. ASECNA needs to go hand in hand
with changes. In Africa, many air ANSPs have unfortunately tended to invest in equipment but
have hardly paid attention to the training needs of the human beings who must operate it.
ICAO has established minimum standards for approved ATC training and has approved
institutions in several African countries like in ASECNA. ASECNA trains part of its
controllers in its own institutions it manages in Niamey, Niger.
However, the total capacity of these institutions is less than 30 per cent of the total
training requirements of Africa. Many African ANSPs are compelled to train their
students in foreign ATC training institutions. Since there is a global shortage of air
traffic controllers, most ATC training institutes outside Africa are fully booked to train
their own nationals to meet local needs. In addition, training fees keep increasing as a
result of growing demand.
3.12 Financing
Figure 3.18: Financial results from 1994 to 2003
0
20
40
60
80
100
120
140
160
180
1994 1995 1996 1997 1998 1999 2000 2001 2003
0
20
40
60
80
100
120
140
160
180
Operating revenue Operating Expenses
Operating Result Operating ratio
Source: ASECNA, annual reports (1994 – 2003)
MillionEuros
%
Chapter 3 Air Navigation Performance review
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One of the major concerns for management of air navigation systems is the financial
requirements for developing countries like in ASECNA. “Member states do not always
have the means to finance air navigation infrastructure improvement as they have other
priorities, such as health, education, poverty reduction” (M. Marafat, ASECNA).
A survey conducted by ICAO's technical cooperation bureau estimated that 97 per cent
of the least developed countries and 83 per cent of the developing states require
technical and financial assistance to improve their air navigation systems (ICAO-Rio
Conference 1998).
ASECNA regularly posts good financial results. Its operating revenue almost doubled
from 1996 to 2003, and its operating ratio is constantly very high (144 per cent on
average during the last 10 years).
3.13 CNS and Aviation Weather Management issues
3.13.1 Shortcomings of conventional systems used by ASECNA
It is recognised that current air navigation systems suffers from technical, operational
and procedural shortcomings, which has serious economic impact on air transport
community. These shortcomings amount to the following factors.
Communications
Despite recent improvements in ATC such as new radar scopes, voice switching
systems, today’s air traffic control primarily relies on a single tool to actually separate
aircraft: a highly congested voice radio frequency. The current ATC system uses
voice communications between air traffic controllers and pilots to relay instructions and
other information critical to operate safely. These communications are necessary to
support coordination of aircraft movements in all phases of flight, to ensure aircraft
separation, transmit advisories and clearances, and to provide aviation weather services.
Skies over international airports are made more dangerous by the lack of standardised
terminology or proficiency levels in English for flight crews and air traffic controllers.
Language confusion is a frequent cause of pilot error. Although English was made the
Chapter 3 Air Navigation Performance review
61
common language of world aviation in 1951, miscommunication and crashes in which
communication was a contributing factor are common. These include ambiguities and
misnomers. Phrases are not derivations of a master plan as they should be. The inability
of English to express specific instructions to pilots without confusion disqualifies it as a
language for permanent use by aviation (Kent Jones, 2005).
One speaker at a time: The voice communications link between controllers and pilots
is similar to a conference call, with the controller and all pilots flying within an airspace
talking over the same channel.
This is very similar to ATC voice communications in congested airspaces. It is not
unusual for pilots to key their microphone and accidentally "step on" the
communication of other pilots or a controller. These are time consuming routine
messages. They waste more time on the ATC voice channel as repeated attempts to
communicate are made. This problem will only get worse as air traffic continues to
increase. Each voice radio exchange takes a certain amount of time for the originator to
transmit and the receiver to respond, and there is a point of saturation where a controller
physically cannot fit in any additional voice radio communications. At this point, no
additional aircraft can be handled within the controller's assigned airspace (Mitre-Caasd,
2005).
Navigation
Fixed airways: Airlines are currently required to plan their flights on the basis of a
fixed route structure, which is largely defined by ground-based navigation aids. The
fixed point-to-point route segments, indirect routings, which rely mostly on ground
based navigation aids, are not the most efficient way of getting from one place to
another. That limits enroute capacity and reduces efficiency. But it has been necessary
because of the limitations in air traffic control technology (Department of Foreign
Affairs and Trade, 2005).
Range Limitations:The current system of land-based navigation requires to over-flight
certain VOR sites, intersections and one-way airways to organize the flow. This means,
Chapter 3 Air Navigation Performance review
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as mentioned previously, that airways depend on the geographic location of navigation
aids. Moreover, airways are like a highway system on the ground. Like the later, at
intersections with crossing traffic, some aircraft can get stuck waiting for the “light to
change” (holding). By creating airways independent of the geographic location of a
ground navigation aid, those airways can be spread out. Spreading the traffic out
increases capacity and safety (Zelechosky et Al, 2005).
Large amount of airspace between each aircraft: Conventional air guidance
systems on board the aircraft and are not precise enough. Therefore, Control centres
have to maintain a 15 minutes horizontal separation between aircraft. As a result, there
is a large amount of space is lost.
Surveillance
Basically, the surveillance systems presently in use can be divided into two main types:
dependent surveillance and independent surveillance. In dependent surveillance
systems, aircraft position is determined on board and then transmitted to ATC. The
current voice position reporting is a dependent surveillance system in which the
position of the aircraft is determined from on-board navigation equipments and then
conveyed by the pilot to ATC by radiotelephony. Independent surveillance is a system
which measures aircraft position from the ground.
Ground-based separation assurance: The Separation ensures that an aircraft
maintains a safe distance from other aircraft, terrain, obstacles. Capabilities include
ground based separation functions on the airport surface and in the terminal, en route,
and oceanic domains. New on-board systems such as the Traffic Alert and Collision
Avoidance System (TCAS) can allow the pilot to execute an evasive manoeuvre. But all
aircraft are not fitted with such systems, especially, local small airlines in regions like
ASECNA area.
Primary Surveillance Radar (PSR): PSR radars operate by radiating electromagnetic
energy and detecting the presence and the character of echoes returned from reflecting
objects. It is an active device using its own controlled illumination for target detection
based on reflected radar energy. However, detection depends on radar cross-section and
line-of-sight and it requires high energy transmission results in costly implementation
Chapter 3 Air Navigation Performance review
63
on ground. The fact that the antennas rotate limits the detection to the beam direction
and suppresses targets within the cone of silence. Moreover, PSRs offer no possibility
to identify the target: It only allows detection. At last, it is very sensitive against
reflections (clutter, sea, weather), and detection depends on a sufficient signal to- noise
ratio.
Secondary Surveillance Radar (SSR): SSR radars transmit coded interrogations to
receive coded data from any aircraft equipped with a transponder. It provides a two-way
data link on separate interrogation and reply frequencies. Replies contain either positive
identification (1 of 4096) or aircraft pressure altitude. But they have similar drawback
to PSRs’ ones. Even the identification is only limited to 4096 codes, and they are
subject to FRUIT (False Replies from Interfering Transmissions), Garble (reply overlap
at the ground receiver) and over-interrogation (due to a high number of interrogators).
All these reduce the probability of detection.
Airport Operations
Airport movements severely restricted during low visibility: During good visibility
conditions the landing capacity of major airports is mainly limited by the final approach
separation minima defined by ICAO, and that sequences accuracy and runway
occupancy times. When the visibility deteriorates and becomes less than a certain limit
the use of landing runways is stopped because pilots cannot maintain visual separation
in case of simultaneous missed approaches for instance (Hans Offerman, 2005).
Moreover, during these conditions, separation requirements between aircraft increase to
avoid runway incursions. All this results into decreased “airport capacity” and increased
controllers’ workload.
Aeronautical information and weather services (AIS)
Disparate formats and standards: The objective of AIS is to ensure the flow of
information necessary for safety, regularity and efficiency of flight operations. In that
respect, each state is required under international agreements to provide this service and
Chapter 3 Air Navigation Performance review
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is responsible for the information provided15. It is provided to pilots in face-to-face
briefings at the aerodrome AIS unit, or in flight, through air traffic control.
Communication of the latest information to users is effected through the aeronautical
fixed telecommunication network (AFTN) in the form of notices to airmen (NOTAM).
This information is however not already available in real time due to technical
limitations.
3.13.2 ASECNA’s systems’ performance
VHF coverage
ASECNA area is 16,000,000 Square kilometres large. A VOR Beacon range is 240 KM.
therefore the number of VORs necessary to cover the entire area is equal to 88.46. This
means that to cover its entire airspace with VHF capability and makes it available for
flights, 89 VORs are necessary. In 2003, ASECNA had only 60 in operation, which
represents 68 per cent coverage of the area. But VHF technics that use VSAT (Very
Small Aperture Terminal) and SATCOM technologies to extend the VHF coverage in
inhospitable areas have improved the situation. Many VSAT have been installed in the
region, and there are other projects under implementation. The most frequently used
means for Aeronautical Mobile Service (AMS - air/ground and air/air communications)
is the HF, which has an extended range but presents drawbacks and the VHF. These
technologies operate well on the whole in ASECNA. But on the one hand, the VHF is
increasingly used and has considerably improved; both from the point of view of quality
and availability (Table 3.6 below), and on the other hand, the HF is still the only
available mean in several sectors, like in the oceanic FIR, and large parts of the Sahara
desert and forests.
The Aeronautical Fixed Service (AFS), which ensures the transmission of flight plans
and other aeronautical messages between specific fixed points, operates fairly well,
15 Conventional aeronautical information services consist on the provision of hardcopy documents in the form of the Integrated Aeronautical Information Package (IAP), which contains information for the entire territory and also areas outside the territory for which a State is responsible for the provision of air traffic services. The information must be provided in a suitable form and must be of high quality, be timely and include, as necessary, aeronautical information of other States. In addition, pre-flight and in-flight information services must be provided.
Chapter 3 Air Navigation Performance review
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especially at main airports. The Fixed Service is often backed up, or replaced by the
SITA16 network, a private network generally used by airlines.
Equipments 2000 2001 2002 2003 Average (%)
Navigation Aids 96.4 96.8 96.9 93.6 95.9
Terrestrial station 96.0 98.2 98.1 98.2 97.6
Communication
Equipments
91.1 94.4 95.8 97.2 94.6
MET Equipments 91.0 92.3 94.5 93.3 92.8
Energy
Equipments
96.0 96.2 98.1 98.1 97.1
Average 93.6 95.4 95.2 95.9 95.0
Table 3.6: Equipments availability in 2003.
Source: ASECNA, annual report, 2003
Transmission speed
The requirement of a minimum modulation rate of 1200 bauds is not met by some main
circuits. The following AFTN main circuits do not meet this requirement: Niamey
/Addis Abeba, Dakar/Casablanca. Tributary circuits connected to the main centres of
Brazzaville, Dakar, Johannesburg and Niamey have been upgraded to higher
transmission speeds, while the outgoing main circuits are operated still at 50 baud.
Use of analogue technology
The level of digitalization is rather low: only 29 out of 65 circuits (44.3%) are digital
circuits in the region, which limits the bandwidth and the data processing capability.
Statistics show that the requirements of 5 minutes maximum for high priority messages
and 10 minutes maximum for other messages are not met most of the time.
Navigation
The main navigational aids in the region operate fairly well. However, many of them
have reached their age limit, especially the Instrument Landing Systems. VORs coupled
or not with DMEs, are implemented in all international aerodromes and are generally
16 Société internationale des télécommunications aéronautiques
Chapter 3 Air Navigation Performance review
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operational. All these ground facilities work towards providing safe navigation in the
ASECNA. Navigation aids equipments’ availability rate (95.9 on average) is below
international standards (Table 3.6). Secondary airports do not often have Landing aids,
and some international airports, like in Equatorial Guinea, do not posses such systems.
Surveillance
The use of radar is very rare in ASECNA area and in West Africa in general. The
explanation given is that ICAO recommends that states should use radar only if the
situation really warrants it. If this is taken as a rule, it would apply to the Gulf of Guinea
States (Ivory Coast mainly). A secondary radar system has been undergoing tests in
Abidjan for the past few years. Its official commissioning has been delayed because of a
problem between the government and ASECNA. It has nonetheless proven very useful.
As an example, recently, a few hours after a recent takeoff from Accra, an aircraft
heading west realized that its navigation instruments were no longer functioning. It
therefore decided to land in Accra, its point of departure. Soon after, it was seen on the
Abidjan radar screens heading north. The Ivorian controllers were able to guide it safely
to its final destination.
Chapter 3 Air Navigation Performance review
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FIRs
ASECNA
Routes Length
in the FIR
(NM)
Controlled routes
Length (NM)
Percentage of
Controlled routes (%)
ANTANANARIVO 9554 5954 62
BRAZAVILLE 11467 8329 73
DAKAR TERRESTRIAL 17471 13826 79
DAKAR OCEANIC 3973 3973 100
NIAMEY 11315 10270 91
NDJAMENA 8349 8163 97.7
Total length 62129 50515 81.3
Table 3.7: Air circulation control: Controlled routes
The absence of radar is strongly felt. Authorities are frequently informed of violations
of their airspace by pilots who come across illegal traffic. They are also aware that
aircraft operators can operate with impunity in their sphere of sovereignty, without their
knowledge. This situation is mainly due to the large number of uncontrolled routes as
shown in table 3.7. Only 81.3 per cent of routes are controlled, and most of them by
conventional means of which limitations have been presented. It can be noted that all
the routes in the oceanic FIR are controlled. These routes are used by airlines flying
from South America to Europe.
In spite of the absence of radar, ASECNA’s air traffic services still provide the classic
elements of control, which is to prevent collision between aircraft in the air and on the
ground, and to speed up and regulate air traffic generally.
Aviation Weather
Table 3.6 reveals that MET equipments’ availability rate (92.8 %) is below international
standards. The performance of weather data collection systems are not better as shown
in the figure 3.19 which represents the system’s efficiency17 in June 2005. Only 68 per
cent of TAF messages were received, and the figures are event lower for METAR
messages, with 43 per cent success. Met stations’ efficiency varies from 77 per cent to
100 per cent. These bad performances have to be link to the poor quality of transmission
systems we presented earlier.
17 Number of messages received on-time divided by the number of messages due to be receive
Chapter 3 Air Navigation Performance review
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Figure 3.19: OPMET availability rate
0
50000
100000
150000
200000
250000
300000
350000
1
Metar required Metar received TAF required TAF received
Source: ASECNA, annual report, 2003
A large number of OPMET messages are received more than 15 minutes after their
transmission. This impacts pilots and controllers’ ability to quickly react in case of
severe weather conditions.
More than 40 per cent of weather irregularities are related to low visibility. Another 40
per cent are due to storms, and the others are windshears, strong winds, and rains. Pilots
are often confronted to these conditions following inaccurate forecasts. Very often they
have to engage deviation manoeuvres. Go-Around, Release, Landing delayed, half turn.
These are extra fuel consuming operations for airlines.
Chapter 3 Air Navigation Performance review
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3.14 Conclusion
The aim of this chapter was to analyse the performance of ASECNA’s air navigation
system, and to highlight its shortcomings. Air navigation characteristics are as follows:
1. Traffic and complexity are increasing, though they remain at low levels when
compared to Europe or North America.
2. The airspace is strongly fragmented at a continental level, though there is relatively
low fragmentation within ASECNA’s own airspace. There is little harmonisation
and more cooperation is required with neighbouring providers to improve cost
effectiveness and deliver a seamless airspace to users.
3. Capacity is not a priority as traffic density and controllers’ productivity remain low
despite projected traffic growth
4. Delays are not the result of air traffic services
5. Safety is the critical issue of concern in ASECNA, as the region, though recent
figures show improvements. The number of safety events remains very high
relatively to the level of traffic. Conventional systems used are often outdated and
unreliable as they do not achieve international standards. It is also shown that
ASECNA is characterised by wide inhospitable areas that render the access to
equipments and their maintenance very difficult.
6. There is not a proper safety management system, and data are not systematically
collected and thoroughly analysed. Safety data are not made available to the public.
7. The use of conventional navigation aids generates flight inefficiency, and is costly
to users. But it would be unachievable to reduce inefficiencies to zero. Performance
targets need to be set, but there is a trade-off to be done with other performance
areas, such as safety.
8. ASECNA’s airspace is used by airlines from around the world. 80 per cent of
ASECNA’s revenues come from foreign or international airlines. This means the
agency must adapt its service, and responds to their needs.
9. ASECNA is relatively cost effective when compared to Europe and the USA. But
there are rooms for improvement as the cost staff costs are very high.
10. ASECNA is a solvent organisation. Its operating ratios and its borrowing power are
good.
70
Chapter 4: CNS/ATM Systems and Concepts
The aim of this chapter is to present the main CNS/ATM systems and concepts, and to
determine suitable solutions for ASECNA, based on experimental performances and
local characteristics.
4.1 Introduction
The process of getting an aircraft safely and efficiently from its origin to its destination
requires effective Air Traffic Management systems supported by three key functions:
Communications, Navigation and Surveillance (CNS). The concept is based primarily
on the following technologies: data link communications, digital aeronautical
information services (AIS), the Global Navigation Satellite System (GNSS) and
Automatic Dependent Surveillance (ADS).
CNS systems are a set of technologies employing digital techniques, including satellite
navigation systems, together with various levels of automation. These are applied to
support a global Air Traffic Management system. The strategic vision is to foster a
global ATM system that enableS airspace users (Aircraft operators), to better meet their
schedules, and to adhere to their preferred flight profiles with fewer constraints. Of
course, this has to be done without lowering the safety levels. These technologies will
enable the transformation of air traffic management to provide for collaborative
decision-making (CDM)1, dynamic airspace management, strategic conflict
management, flexible use of airspace and all weather operations.
The airline industry is looking for ways to improve its bottom-line profitability as
shown in chapter 2. It is focusing its efforts on the need for change. One Sky, global
ATM is the industry's vision of a global air navigation system that improves Safety and
Efficiency whilst accommodating worldwide air traffic growth in an airspace that is
1CDM brings together airlines, civil aviation authorities and airports in an effort to improve air traffic
management through information exchange, data sharing and improved automated decision support tools. This philosophy of collaboration promises to become the standard in aviation. CDM enables information sharing and facilitates decision making processes by ensuring that stakeholders are provided with timely and accurate information, essential for the planning of their operations (IATA)
Chapter 4 CNS/ATM systems and concepts
71
seamless and devoid of national borders. According to IATA, achieving this vision will
result in a wide range of benefits such as, environmental benefits (Reduced emissions),
and lower overall costs for the airlines through operational improvements, efficiency,
avionics equipage and equitable user charges.
Therefore, CNS/ATM systems are crucial to the industry, in their attempt to simplify
the business, and to gain more freedom in the way they operate.
ANSPs expect that better communications, navigation and surveillance systems will
undoubtedly increase the level of safety. With the use of voice and data
communications, satellite and precision navigation, SSR Mode S and ADS surveillance,
and all the other new concepts, ANSPs will significantly reduce the hazards due to the
use of conventional systems.
A common digital aeronautical information exchange model is the industry’s objective.
The new systems make possible the sending of right information to the right user at the
right time. Particularly, satellite technology and data link provide, where it is used for
aviation weather purposes, a highly reliable, fast and efficient method of
communication. Faster and more-efficient transmission methods ensure that much more
information can be made available. Suppliers of meteorological aviation data can
therefore provide a more comprehensive service to airline operators.
Capacity will be increased thanks to the implementation of new ATM practises and
concepts. RVSM (reduction of vertical separation limits) has already brought
consequent capacity gains where it is been applied (In Europe and Northern America
for instance). More capacity also means increased safety margins in non-congested
airspaces.
States consider Air transport industry as a critical component, and a development tool
for their economies as explained in chapter 2. A performing and safe air navigation
system that can absorb air traffic growth and guarantee safety must be considered as a
matter of strategic importance. Developing states like those in ASECNA are provided
with a timely opportunity to enhance their air navigation infrastructures. Countries in
ASECNA, as many developping nations continue to have large parts of their airspace
available but unsusable because they are unsafe as shown in chapetr 3. This is due to the
cost of maintaining the necessary ground infrastructure. According to ICAO,
Chapter 4 CNS/ATM systems and concepts
72
CNS/ATM systems offer them opportunities to modernize at a low cost, their air
navigation system. Moreover, the impact of air transport on environment increases with
the industry’s growth. States are committed to reducing aviation emissions. By allowing
efficient aircraft operations and fuel consumption reduction, CNS/ATM systems appear
to be a part of solution to achieve that goal. That’s why states have to assist the industry
in that modernasation process, by facilitating financing and cooperation.
4.2 Suitable CNS/ATM systems for ASECNA
The following tables summarize ASECNA’s characteristics and indicate the
corresponding current solutions used, and CNS/ATM alternatives, that are supposed to
bring significant improvements.
4.2.1 Geographic characteristics
Characteristics Current systems CNS/ATMInhospitable areas
Deserts HF , Deported VHF CPDLC, ADS-B, ADS-COceans HF ADS-B, VDL, HF data linkForests HF, Deported VHF ADS-B, VDL, HF data link
4.2.2 Efficiency
Characteristics Current systems CNS/ATMFixed routes VOR, DME, NDB GNSS, RNAV, RVSM,
RNPFuel Inefficiency VOR, DME, NDB CPDLC, RNAV, RVSMLow airport accessibility ILS, DME GNSS
FragmentationDuplication of Equipments, Separated Civil aviation authorities
Regional Harmonisation
MET data accuracy Low Speed Transmission, AFTN
Digital Transmission, ATN
Controllers’ Productivity ATC ATM, CPDLC, ADS-B
Chapter 4 CNS/ATM systems and concepts
73
4.2.3 Capacity for Safety
Characteristics Current systems CNS/ATM
Poor safety records
Voice Communication, Ground based separation assurance, strips, primary
radars
Data Link, CPDLC, Radars mode S
4.2.4 Surveillance
Characteristics Current systems CNS/ATMPoor surveillance Primary radars, Voice
reportingADS-B, HF data link, radars mode S
Runway incursions Visual surveillance Multilateration
Range limitation Satellite based VHF, HF AMSS
4.3 Study of selected systems
4.3.1 Communication systems
The communication requirements for each phase of flight depend on the controller-pilot
communication needs. These requirements vary with the traffic complexity and density,
the weather conditions, the controller’s needs to issue clearances and vector2 the
airplane or to establish contact with the aircraft crew. Enhanced communication
performance is provided through air-ground data link communications integrated into
the Aeronautical Telecommunication Network (ATN) to complement the current voice
communications means (see ATN page 83). Voice communication will be used for
critical messages, such as vectoring to avoid traffic and landing clearance at airports
with heavy traffic. It will also serve as back up.
2 Headings by the ATC to an aircraft, for the purpose of providing navigational guidance
Chapter 4 CNS/ATM systems and concepts
74
Figure 4.1 : Aeronautical communication links
Data Link
A key feature of communication is the use of digital Data Link as a primary means for
exchanging aeronautical information and delivering ATC services: pre-departure
clearance (PDC), digital Automatic Terminal Information Service (ATIS), selected
Flight Information Services (FIS) and oceanic ATC services for instance. Today’s most
prominent Data Link advanced features are CPDLC and VDL, Mode S Data Link.
CPDLC (Controller Pilot Data Link Communication)
CPDLC is an important tool that addresses the problems generated by the growth in
aviation communications and the accompanying needs for effective communications,
and acceptable safety levels (Hancock, 2005). CPDLC resolves a number of drawbacks.
For instance, it provides automatic data entry capabilities. This permits ground systems
and airborne flight management computers to enter critical information, such as flight
routes… etc. It cuts down on errors resulting from manual data entry. It also permits a
significant reduction in transmission time, thus reducing the congestions. It eliminates
misunderstanding due to a deficient quality of the voice received, propagation problems,
dialects and the possibility of having instant access to previous voice transmission
recording. The following figure represents a screen shot of a CPDLC message between
CCoommmmuunniiccaattiioonnss
Ground: ATC, ANSPs, AOC
Aircraft 1
Satellite
Aircraft i
Ground: ATC, ANSPs, AOC
Chapter 4 CNS/ATM systems and concepts
75
a controller and a Pilot. The ATC ask the pilot to climb at a certain altitude, and the
pilot replies that the aircraft performance could not tolerate this manoeuvre.
Figure 4.2 CPDLC test message on SAS3 B737-600 LN-RRZ MCDU
Source: SAS, 2005
CPDLC Trials
As explained, CPDLC supplements the essential communications bridge between
controllers and pilots. It helps to reduce routine workload, non-time critical exchanges
from the voice channel to a data channel, freeing the voice channel for time critical
communications such as vectors around weather or traffic.
Voice channel occupancy: In high fidelity simulations conducted at the Federal
Aviation Administration's (FAA) Technical Centre, the voice channel occupancy
decreased by 75 percent during realistic operations in busy en route airspace. The net
result of the decrease of voice channel occupancy is increased flight safety and
efficiency through more effective communications between controllers and pilots, with
fewer missed, repeated, and misunderstood communications.
Capacity Gains and Workload reduction: A real-time simulation performed at
Eurocontrol’s experimental centre during the year 2000 investigated the use of voice
radio frequency at three levels of traffic volume: baseline study day traffic, and 150%
3 Scandinavian Airways
Chapter 4 CNS/ATM systems and concepts
76
and 200% of the baseline volume, and at four levels of Data Link aircraft equipage: 0%,
50%, 75% and 100%. A clear positive correlation was obtained between aircraft
equipage level and reduction in voice frequency usage. The following figure presents
the results (Boeing, 2000).
Figure 4.3: Estimated Capacity gained as a function of percentage of CPDLC
equipage
Source: Mitre Corporation, 2005
Working with these data, Eurocontrol used findings from previous non-data link studies
conducted by National Air Traffic Services (NATS), in the United Kingdom and the
Centre d'Études de la Navigation Aérienne (CENA) in France to estimate reductions in
total sector workload associated with communication under current voice-only
conditions (table 4.1). These earlier results indicated that communications normally
constitute 35% to 50% of total sector workload. Based on the reductions in frequency
usage previously identified in the real-time simulation, Eurocontrol calculated total
sector workload reduction due to CPDLC for each level of data link equipage using the
conservative estimate of communications workload (35%). The link between sector
workload and airspace capacity was estimated using prior results obtained with an ATC
Capacity Analyser tool.
Chapter 4 CNS/ATM systems and concepts
77
Table 4.1 Workload reduction as a function of aircraft equipage(Boeing, 2000)
The results suggested that proportional sector capacity increases are approximately
one-half of the amount of workload reduction achieved in a sector. The results of the
workload reduction calculations performed by Eurocontrol in 1999 are presented in
table 4.1 above.
Delays reduction: Eurocontrol investigated the impact of traffic and capacity variations
on Air Traffic Flow Management (ATFM) delays in the European airspace. The traffic
sample and the airspace used for the delay calculations were identical to those used in
the real-time simulation baseline described previously. The results are shown in table
4.2 below.
Table 4.2: Delays Reduction as a Function of aircraft Equipage
(Boeing, 2000)
As suggested earlier, future efforts should allow to identify and to quantify benefits that
will be gained not only by airspace users, but also by ANSPs. For the later, benefits
flow directly from the increase in productivity (controllers’ workload, capacity)
associated with the use of CPDLC. However, they are realized as an alternative means
to increase airspace capacity without increasing the number of en-route control centres.
The keys to assessing the benefits of CPDLC lie in an understanding of how CPDLC
facilitates the job of air traffic controllers, and how these changes affect the effective
capacity of airspace and the associated costs of maintaining a safe and efficient air
traffic system and the cost of using it.
Percentage Aircraft Equipage Workload Reduction0% 0%
50% 16%75% 22%
100% 29%
Percentage Aircraft Equipage
ATFM Delay reduction Overall Delay reduction
0% 0% 0%25% 10% 2.5%50% 31% 8%75% 44% 11%100% 53% 13%
Chapter 4 CNS/ATM systems and concepts
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The physical infrastructure that supports the CPDLC is the VHF Data Link (VDL)
presented below.
VHF Data Link (VDL)
VHF analog communication means available today are not compatible with CNS/ATM
technologies. VHF Data Link operations require a VHF digital radio. VDL is essential
for Data Link; VDL formats specify a protocol for delivering data packets between
airborne equipments and ground systems similar to that used in Aircraft
Communication Addressing and Reporting SystemS (ACARS). The difference is that
VDL provides a capacity 10 times greater than the equivalent of 25 KHz VHF channel.
VDL Mode 1: VDL mode-1 is a low speed bit oriented data transfer system. It uses
carrier sense multiple access (CSMA4) protocol. The new development has overtaken
VDL mode-1, which is no longer in use.
VDL Mode 2: It is an improved version of VDL Mode 1 and it uses the same
technology and Differential 8 Phase Shift Keying (D8PSK) modulation. It is supported
by VHF and HF capabilities. Its average data transmission is 31.5 kbps5. This is over 13
times the VHF ACARS 2.4 kbps rate using Double Sideband Amplitude Modulation
(DSB-AM). It employs a globally dedicated common signalling channel6 (CCS) of
136.975 MHz.
VDL Mode 3: it is an integrated digital data and communication system allows to use
up to four voice and/or radio channels on a single carrier with 25 KHz spacing. The data
link technology used is called TDMA7. The data capability provides a mobile sub
network that is compliant to the Aeronautical Telecommunication Network.
4 Carrier sense means that every device on the network listens to the channel before it attempts to transmit the information. Multiple access means that more than one network devise can be listening at the same time, waiting to transmit the data. 5 Kilo Byte per second
6 Signalling is the use of signals for controlling communications. CCS means that a data channel in combination with its associated signalling terminal equipments. It only requires one signalling channel for up to 1000 data communication channels and is able to do this by only signalling when required.
7 TDMA is a technology for delivering digital wireless service using time-division multiplexing (TDM). TDMA works by dividing a radio frequency into time slots and then allocating slots to multiple calls.
Chapter 4 CNS/ATM systems and concepts
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VDL Mode 4: It uses a data link technology called self-organizing time division
multiple access (STDMA). In this mode, stations transmit their geographical position
together with data message in time slots that are dynamically modified at frequent
intervals.
Before starting a transmission using the STDMA technique, the aircraft keeps listening
on the frequency to be used and establishes a track and a table of time slots for all other
aircraft. An algorithm in the aircraft transceiver selects a free slot or takes the slot of the
most distant aircraft. This modulation system allows distant stations to transmit in the
same slot with little interferences. The aircraft is not involved in any manual frequency
tuning for any station change. Reception of the geographic position gives a surveillance
capability. VDL mode 4 is a candidate technology for ADS-B operations.
Airlines prefer VDL Mode 2. The technology is perceived as the only logical choice
because it is a globally accepted standard supported by the communication service
providers such as SITA8 and ARINC9. VDL Mode 2 has been standardized as a digital
data link to be shared by Air Traffic Services (ATS) and Aeronautical Operational
Control Centres (AOC). This is done within the framework of ICAO’s standardized
Aeronautical Telecommunications Network (ATN).
Mode S Data Link (Mode Select)
Mode S is use for surveillance as it’s will be explained later in page 96. Nevertheless, it
also makes available an air-ground data link, which can be used by ATS in high-density
airspace.
Mode S Transponders send and receive data link messages via Mode S message
formats. During normal operation, ATC ground stations and other aircraft automatically
receive altitude, discrete address, and transponder code via interrogate and reply
formats.
8 Societe International des Telecommunications Aeronautiques
9 Aeronautical Radio Inc
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The Mode S ground interrogator transmits a sequence of pulses. The timing, the level
and the sequence of the pulses determine the interrogation mode. The ground
interrogator can distinguish between the surveillance function and the data link function
due to the availability of different pulses, pulse amplitudes and pulse times. Mode S
data link function uses four distinct pulses.
Aeronautical Mobile satellite System (AMSS)
AMSS are geostationary communications satellites, designed especially for mobile
communications, which offer wide/near global coverage and voice and data
communications. The digital voice component of AMSS is designed to interface with
terrestrial public switched telephone network (PSTN) and to provide high quality
telephone service both for aeronautical passenger communications (APC), ATS &
Aeronautical operational control (AOC). The use of AMSS is particularly suitable for
cross-oceanic flights.
High frequency Data Link (HFDL)
The HF data link provides an air-to ground data link that is ATN-compatible. Its
development within lCAO has progressed rapidly and appears to provide an alternative
and possibly cheaper communication medium than SATCOM for data. HF data link is
also an excellent standby system for the AMSS presented above, in oceanic and remote
areas. Aiircraft can contact three or more HFDL ground stations constantly and its hub
can become ATN routers. The dependence on HF voice continues to remain the
backbone for ANSPs communication systems in oceanic and remote regions.
AMSS, VDL, Mode S and HF data link use different data transmission techniques.
Individually, they all use the same network access protocol in accordance with
International Standardization Organisation (ISO). This allows the interconnection
between these technologies and other ground-based networks. The communication
service that allows ground, air-ground and avionics data network to interoperate is the
Aeronautical telecommunication Network presented in figure 4.4.
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Aeronautical Telecommunication Network (ATN)
“Without ATN, there is no CNS/ATM”. (Dr Hilaire Tchicaya, Head of Aeronautical
Telecommunications, ASECNA). In fact, ATN is the inter-networking infrastructure for
the technologies presented above and others. ATN will link the various air-ground data
systems together.
A variety of ground networks, implemented by states, a group of states or commercial
networks that use packet switching techniques and are compatible with ISO’s OSI
reference model will be able to use ATN’s internetworking services. With the gradual
implementation of ATN, the use of the current Aeronautical Fixed telecommunication
network that serves to transmit messages between ANSPs, and between ANSPs and
users. AFTN will diminish. However, during the transition period, interconnection of
AFTN terminals to the ATN will be possible via special gateways.
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Figure 4.4 Aeronautical Telecommunication Network concept
Source: ICAO, 2002, p.69
ATN allows communication between all the stakeholders. The design provides for
incorporation of different air-ground sub networks and different ground-ground sub
networks, resulting in a common data transfer service. The two aspects are the basis for
interoperability that will provide a reliable data transfer service for all users.
Furthermore, the design is such that user communication service can be introduced in an
evolutionary manner.
As shown in Figure 4.4 above, the routing of messages over ATN are controlled by
routers. The routers direct data messages to their destinations. ATN aims at operating
globally, encompassing all aeronautical data communication services.
FMS
ATSAirline Operation Control
Airline Admin Service
AirlineData Base
Cabin Crew Interface
PAX Interface
Flight crew Interface
Airborne Network
VHF Link
Satellite Link
Mode S Link
Router
ATFM
Router
Private Ground Network
ATS ground
NetworkGateway to PDN
Gate Link
HF Link
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4.3.2 Navigation systems
CNS/ATM navigation technology improves the accuracy of the position and provides
better predictions of future positions to enable aircraft to fly more accurately..
Improvements in navigation include the progressive introduction of area navigation
(RNAV) and required navigation performance (RNP) capabilities along with the global
navigation satellite system (GNSS). These systems provide for worldwide navigational
coverage and are being used for en-route navigation and for non-precision approach.
With appropriate augmentation systems and related procedures, it is expected that these
systems will also support precision approaches even under bad visibility conditions.
Global navigation satellite System (GNSS)
GNSS is a satellite system that is used to pinpoint the geographic location of a user's
receiver anywhere in the world. Two GNSS systems are currently in operation: the
American system: Global Positioning System (GPS), and the Russian's Global Orbiting
Navigation Satellite System (GLONASS). A third one, Europe's Galileo, is slated to
reach full operational capacity in 2008. Each system employs a constellation of orbiting
satellites working in conjunction with a network of ground stations.
Satellite-based navigation systems use a version of triangulation10 to locate the user,
through calculations involving information from a number of satellites. Each satellite
transmits coded signals at precise intervals. The receiver converts signal information
into position, velocity, and time estimates. Using this information, any receiver on or
near the earth's surface can calculate the exact position of the transmitting satellite and
the distance (from the transmission time delay) between it and the receiver.
Coordinating current signal data from four or more satellites enables the receiver to
determine its position. There are nearly 30 satellites giving an accurate positioning and
timing information worldwide. They can be used to give positioning accuracies of better
than 10 metres and timing accuracies of better than 30 nanoseconds.
World Geodetic System coordinates (WGS-84): An important tool in implementing
these navigation principles are the World Geodetic System coordinates (WGS-84).
10 Triangulation is a process by which the location of a radio transmitter can be determined by measuring either the radial distance, or the direction, of the received signal from two or three different points. Triangulation is used in aviation to pinpoint the exact geographic position of an aircraft for instance.
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WGS-84 coordinates system is a conventional earth model, established in 1984 from
assembled geometric and gravitational data. This model portrays the earth as being
ellipsoidal, contradicting former beliefs that the earth was spherical (ASECNA, 1996).
The origin of this system is the earth's Centre of mass (assuming for simplicity that the
earth rotates at a constant speed around a fixed meridian pole).
The WGS-84 system responds to the present navigational needs: RNAV, RNP, ATS
routes and satellite navigation. In 1989, ICAO adopted WGS-84 as the standard
geodetic reference system for future navigation (For further information, refer to
Appendix 3).
Satellite Based augmentation Systems (SBAS): There are four Satellite Based
Augmentation Systems being developed: EGNOS in Europe, GAGAN in India, MSAS
in Japan and WAAS in the USA. These are all civil-controlled regional systems and
there is a form of coordination to ensure that they are interoperable to provide a
seamless worldwide navigation system so that one SBAS/GPS receiver can be used all
of them. Each SBAS provides GPS corrections to improve positioning accuracy to
around 1 metre horizontally and 3 metres vertically. Timing accuracy is enhanced to
better than 10 nanosecondes.
ASECNA has chosen the European Augmentation Systems EGNOS as part of his
satellite navigation strategy.
European Geostationary Navigation Overlay Service (EGNOS): EGNOS, the
European Geostationary Navigation Overlay Service, is a SBAS that is being deployed
to provide regional satellite-based augmentation services aviation, maritime and land-
based users in Europe. EGNOS is the first step in the European Satellite Navigation
strategy that leads to Galileo. Availability is improved by broadcasting GPS look-alike
signals from up to three geostationary satellites; accuracy is improved to between 1 and
2 metres horizontally and between 2 and 4 metres vertically; Integrity and Safety are
improved by alerting users within 6 seconds if a malfunction occurs in EGNOS or GPS.
The following are the benefits that are derived from EGNOS.
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Figure 4.5: Comparison between EGNOS and GPS
Source: ESA, 2004
EGNOS enables Precision Approach Operations (APV 2 and APV 1)11. They are
achievable on every runway. The Integrity of EGNOS vertical guidance protects aircraft
against CFIT12 accidents. Thanks to SBAS APV1, all non-precision approach (NPA)
procedures are suppressed. New SBAS APV1 services open the door to new feeder
routes between secondary and inter national airports. New APV1 procedures suppresse
the need of CAT-1 service for many runways
A major advantage of this system is that it requires less costly ground installations than
is required by present conventional systems. It allows the full coverage of navigational
services over sparsely populated, desert and forest areas. It must be highlighted that
there is no technical requirement for the implementation of EGNOS ground stations in
each African country. In other words, this means that EGNOS service provision scale is
at regional (i.e. sub-continental) supra-national level.
11 Approach Procedure with Vertical guidance12 Controlled Flight Into Terrain
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EGNOS Trials
The aim of the flight trial was to assess EGNOS’ capability to provide aircraft guidance
during two different approach types:
1) Straight-in ILS look-alike approaches: Guidance was provided by the
flight director and autopilot of the aircraft’s Flight Management System.
2) Curved approaches: Guidance was provided by the flight director of the
Research
The following parameters among others that are not reported here have been
investigated:
Accuracy: The navigation system error (NSE13), the total system error (TSE14),
Integrity, and Noise Contour.
13
The navigation system error (NSE) is defined as the difference between the actual flight path (i.e. Trimble reference position) and the flight path indicated by the navigation system in the lateral and vertical plane.
14The Total System Error (TSE) is defined (See figures above) as the difference between the desired
flight path and the actual flight path (i.e. Trimble reference position).
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The Results
The Total System Error (TSE)
Figure 4.6: Lateral and Vertical TSE for three approaches. (Red=1st approach, Green = 2nd, Blue = 3rd approach. A minus sign means Left/Below
desired position; a plus sign means right/Above desired position).
The performance in terms of the Horizontal NSE and the Vertical NSE were found to be
in the order of 1-4 m (95%) in the lateral and vertical plane and can be rated as very
good according to Eurocontrol. The lateral APV-II and CAT I requirements as specified
in ICAO SARPs were easily met (tables 4.3, 4.4 and 4.5 below). The vertical APV-II
criteria specified in the SARPs were met during all curved approaches.
95% AccuracyProcedure Lateral (m) Vertical (m)
Nice results 3.9 4.9
95% AccuracyICAO SARPS APV I APV II CAT I
Lateral (m) 220 16 16Vertical (m) 20 8 4-6
AvailabilityAPV I APV II CAT I
Nice 100% (100-99,92) % 100%ICAO 0.9999 0.9999 0.9999
Distance to the runway Distance to the runway
Table 4.3
Results for lateral vertical accuracy
Table 4.5: ICAO’s SARPs for lateral and
vertical accuracy
Table 4.4
Results for Availability Vs ICAO’s SARPs
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In general, the aircraft arrived at the runway threshold slightly right of centreline during
the curved approaches. The navigation system error was relatively small.
Noise Contour: This noise impact study confirmed that the Riviera approach reduces
annoyance for the local area, especially at the located right below the ILS eastward
approach trajectory. The study also revealed that the use of a SBAS navigation system
might bring further improvements around the southeast local area by considerably
reducing the dispersion of aircraft trajectories. However, for the SBAS scenario all
aircraft were assumed to have the same 3D trajectory, which is a strong assumption.
The benefits of SBAS guidance in terms of noise will strongly depend on the way it is
implemented and how pilots and controllers respect procedures.
GNSS and improvements in avionics allow better navigation and approach manoeuvres.
Area Navigation and Required navigation performance are two of the main concepts
made possible by these CNS/ATM tools.
RNAV (Area Navigation)
Area Navigation is a method of navigation that enables an aircraft to fly in any desired
path within the coverage of referenced air navigation aids, or within the capacity of self
contained systems or a combination of both. The use of routes and procedures based on
RNAV, improves access and flexibility, through point-to-point navigation. These routes
are not restricted to the location of ground based NAVAIDs. Safety of such operations
is achieved thanks to a combined use of navigation accuracy, ATC monitoring,
communication, multilateration15, or increased separation.
RNAV was developed to provide more lateral freedom and a better use of available
airspace. This method of navigation does not require a track directly to or from any
specific radio navigation aid as explained above, and has three principal applications:
1) A route structure can be organized between any given departure and arrival
point to reduce flight distance and traffic separation.
15 Multilateration is today’s version of triangulation (use of three satellites to locate an object), where the location of an object is determined by taking its bearing from several different places.(Refer to appendix 2 for more details)
Chapter 4 CNS/ATM systems and concepts
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2) Aircraft can be flown into terminal areas on varied pre-programmed arrival
and departure paths to expedite traffic flow.
3) Instrument approaches can be developed and certified at certain airports,
without local instrument landing aids at that airport.
The following figures represent the navigation performance when using RNAV or RNP.
They clearly show the advantages of new systems in term of efficiency.
Figure 4.7: Comparison between RNAV, RNP and Conventional navigation
Source: Federal Aviation Administration, 2006
Trials have been conducted and RNAV is already implemented in many parts of the
world since the year 2000. The following are the results from trials in Atlanta (USA).
RNAV Trials
As the next figure depicts it, Non RNAV flights are characterised as follows:
1) Departures are vectored
2) Headings, altitudes and speeds issued by controllers
3) Large number of voice transmissions required
4) Significant dispersion
5) Tracks are inconsistent and inefficient and there are limited exit points
Optimised Efficiency with
RNP
Improved Efficiency with
RNAV
Inefficiency with Conventional
systems
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Results
Figure 4.8: Atlanta SID trials: Non RNAV tracks
Source : IATA, 2005
Flights with RNAV capabilities give the following results:
Figure 4.9: Atlanta SID, RNAV tracks
Source: IATA, 2005
The results are as follows:
Departures fly RNAV tracks are not vectored
Headings, altitudes and speeds are automated via avionics
Voice transmissions reduced by 30-50%
Reduced Track Dispersion
Tracks are more consistent and more efficient
Additional exit points available
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RNP (Required Navigation Performance)
RNP operations are RNAV operations that use on-board containment16 and
monitoring. The ability of the aircraft navigation systems to monitor its achieved
performances, and to indicate to the crew whether the operational requirement is being
met during an operation, is a critical component of RNP. Aircraft RNP capability is
important in determining the separation requirements to ensure that containment is met.
RNP approach is already being implemented in some American airports.
In the Caribbean and Latin America regions, introduction of RNAV is generating an
annual reduction of around 40,000 tonnes of CO2 emissions. In cross polar-routes,
satellite based navigation has enabled flights over previously untravelled territory using
Russian, Canadian and US airspace close to the North Pole. The first official polar route
flight between North America and Asia by a commercial airline was conducted in July
1998. Currently, more than 200 flights per month use near polar routes between Europe
and Asia and Asia and North America thereby benefiting airlines and passengers
through significant time and fuel savings and associated emissions reductions.
Figure 4.10: Projected RNP-RNAV capability, RNP capable aircraft:
Source: Eurocontrol, 2002
16 Onboard containment is onboard alerting and monitoring capability that reduces the reliance on Air Traffic Control intervention, via Radar or ADS, multilateration…
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American and European aviation regulators have recently approved the integrity of
navigation data provided by Boeing. It enabled carriers to use the information for
precision area navigation procedures: Carriers using the navigation data will be able to
implement new precision area navigation (P-RNAV) procedures. They require that
aircraft are able to maintain a track with lateral accuracy of 1nm (1.85km) for 95% of
the time (Kaminski-Morrow, August 2005)
As the figure 4.10 suggests, aircraft RNP and RNAV capability will be greater than 90
per cent by 2010. Which means no ANSP could ignore that, and therefore they need to
prepare themselves consequently to be able to offer that service to their users.
RVSM (Reduced Vertical Separation Minimum)
The goal of RVSM is to reduce the vertical separation above flight level (FL) 290 from
the current 2000-ft minimum to 1000-ft minimum. This will allow aircraft to safely fly
more optimum profiles, gain fuel savings and increase airspace capacity. The process of
safely changing this separation standard requires a study to assess the actual
performance of airspace users under the current separation (2000-ft) and potential
performance under the new standard (1000-ft).
RVSM was successfully implemented across 41 European and North African States in
January 2002. During the first summer of operations, ATM capacity in European
airspace was increased by approximately 15%.
4.3.3 Surveillance systems
Secondary Surveillance Radars are still being used, along with the gradual introduction
of Mode S presented below, in both terminal areas and high-density continental
airspace. The major innovations are the introduction of Automatic Dependent
Surveillance (ADS), Mode S surveillance and multilateration. The latter is not
presented here although it has great potential.
ADS systems allow the aircraft to calculate its position, its heading and other data such
as speed and useful information contained in the flight management system. The data
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are automatically transmitted to the air traffic control unit. ADS data are transmitted via
satellite or the communication means presented earlier (Data Link…). The position of
the aircraft is displayed on a screen like with a radar display. ADS is defined as the true
merging between Navigation and Communication technologies. Along with enhanced
ground systems’ automation, ADS helps to improve ATM, especially in oceanic
airspaces.
The need for new HF radios on Atlantic routes has been averted through the gradual
introduction, over the past few years, of ADS waypoints reporting, which allows better
flight plan conformance monitoring and a reduction in gross navigation errors.
There are presently three types of ADS: ADS-A, ADS-B and ADS-C. These are
presented below.
ADS-A (Addressable)
ADS-A enables appropriately equipped aircraft to send position information messages
at predetermined geographical locations or at specified time intervals. ADS-A can be
relayed via high frequency data link, satellite communication, and very high frequency.
Some pacific ATS providers already use Automatic Dependent Surveillance-
Addressable to apply 50 nm longitudinal separation between aircraft. ANSPs’ systems
in countries like New Zealand, Australia, Tahiti, and Fiji support the use of FANS 1/A
ADS-A operating systems in Pacific oceanic airspace (Cirillo, 2004).
ADS-B (ADS-Broadcast)
ADS-B involves broadcast of position information to multiple aircraft or multiple ATM
units. ADS-B-equipped aircraft or ground vehicle periodically broadcast their position
and other useful data derived from on-board equipments. This is called aircraft derived
data (ADD). The position is calculated through GPS and associated augmentation
systems. Any user, either airborne or ground-based, within range of this broadcast, can
process the information. It will remove the reliance on voice reports and is expected to
add significant en-route safety. The technology is also envisaged to be applied for
surface movements, thus being an alternative to surface radars such as airport surface
detection equipment.
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Figure 4 .11: ADS-B operational capabilities.
Source: RockwellCollins.com
The figure above (figure 4.11) illustrates the operational capabilities of the technology.
It will bring significant operational enhancement in airport surface management, air-to
air and air-to-ground communications, and in surveillance operations. On airports’
surface, it will enhance pilots’ situation awareness, and above all, it will reduce
runway. In-flight, ADS will improve separation standards.
ADS-B Operational trials (Bundaberg, Australia)
In recent years, Australia has been active in the field of automatic dependent
surveillance-broadcast because the technology offers the possibility of continent-wide
coverage.
In 2002, Air Services Australia installed a single ADS-B ground station at Bundaberg
and equipped a number of aircraft with ADS-B avionics. They modified Australian
ATM system to process and display ADS-B tracks. The data link technology used was
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95
Mode S extended squitter17. The focus of Bundaberg’s trials was to improve lower level
surveillance coverage to allow early insurance of clearances as aircraft climbed into
controlled airspace. 28 ADS-B ground stations are planned nationwide. Some will
replace 11 secondary surveillance radars, saving a fortune in maintenance cost. Each
ADS-B station costs $1 million. It will replace a $US10 million worth radar that
costs $US1 million per year to maintain. The other ADS systems will provide
coverage in airspace that has never had radar.
Results
The systems performance exceeded expectations. Detection coverage, position
accuracy, velocity vector accuracy and update rate were found to be better the
conventional fast rotating monopulse secondary surveillance radar used (Dunstone,
2005).
Gotzenhein (Germany) Operational trials
This site was chosen because Frankfurt had been evaluated as the region with the
highest FRUIT density world-wide. The ADS-B antenna elements were positioned
either side of the airport radar tower for 360° coverage.
Results
Evaluated as a Terminal application (100 Nm) with a 4 second update rate,the
Probability of Detection (Pd) was greater than 99.8%.
Evaluated as an En-route application (150 Nm) with a 6-second update rate, the Pd was
above 99.6%.
As shown on the following figure (Figure 4.12), ADS-B is far better than Radar. While
radar data gated to 150 NM, ADS-B was only limited by terrain screening. The results
also showed a higher update rate, which allow a better accuracy (Wakefield, 2005).
17 Works on 1090 megahertz, and is recommended as initial worldwide interoperable ADS-B Link
Chapter 4 CNS/ATM systems and concepts
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Figure 4.12: Comparison between ADS and Radar’s.
Source: Wakefield, 2005
ADS-C (ADS-Contract)
ADS-C is another ICAO standardised technique that allow aircraft to report data
items, including position, identity, intent, etc, to the ground over a point-to-point
data-link. It has been deployed mainly in oceanic areas and uses satellite
communications. However, it can also be used over any point-to-point data-link
(VHF, HF… etc). The technology is presently used only in areas of low traffic
density because of bandwidth limitations in point-to-point data-links.
Secondary Surveillance Radar Mode S (SSR-Mode Select)
Mode S radar is a relatively new type of secondary radar that is also based on the use of
a transponder on board the aircraft, responding to interrogations from the ground. The
radar thereby detects the aircraft with better link means, and above all retrieves
information that can help identify the aircraft at the same time.
Communication between conventional secondary radar and a conventional transponder
uses the modes A and C. When interrogated in mode A, the transponder replies by
Chapter 4 CNS/ATM systems and concepts
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transmitting its code with the same name (allocated to the flight by air Traffic Control,
and entered by the pilot into the transponder via the interface). When interrogated in
mode C, the transponder replies by giving its altitude.
The radar mode S operates at the same frequencies (1030/1090 MHz). The Mode S
provides more accurate position information and minimizes interferences by discreet
interrogations of each aircraft. Its selectivity is based on precise identification of an
aircraft by its 24-bit address. That address can be considered as its communication
address and is linked to the aircraft, or at least to its transponder. But it does not replace
the Mode A code which is linked to a flight or a flight plan. There are also plans for
recovery of the A and C codes via Mode S.
4.3.4 Air Traffic Management
The future domestic ATM
Using satellite-based navigation and communication networking technologies presented
above, the future domestic and oceanic ATM systems will be seamless. They will
employ similar systems and procedures regardless of location. However, complete
transition to the new environment may not be completed in the near term. Therefore, the
near-term domestic CNS concept must maintain some reliance on current ground ATC
capabilities, albeit upgraded, particularly in terminal areas. Terminal air traffic
controllers will continue to separate and sequence aircraft. Pilot-controller connectivity
will include both voice and data. Radar will continue to provide some aircraft position
information but the introduction of Mode S secondary radars will facilitate the selective
interrogation of aircraft. In addition, ADS-B will be introduced in the en route structure
where aircraft broadcast position information derived from GPS and corrected by
augmentation systems to the ATM system. SBAS corrections will be transmitted from
ground earth stations through communications satellites. GPS and Augmentation
systems may also provide precision approach information in the future for aircraft,
eliminating the need for ILSs and precision approach radar (PAR). Data link
networks will route CNS data as presented earlier.
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The future oceanic ATM
In the near future, the greatest changes will occur in the oceanic environment. Here we
expect the full implementation of satellite-based CNS (ADS, Data-Link… Etc). Aircraft
will relay GPS/Augmentation-derived positions to ATM systems through satellites. The
same satellites will be used to relay aircrew requests and ATC instructions, many of
which will involve ATM to aircraft data links. The data link network will route CNS
information accordingly. In the oceanic environment, the first implementation of
aircrew-based separation is expected. Today, some airlines are already using a TCAS
“in-trail climb” procedure in which aircrews coordinate manoeuvres that allow aircraft
to pass one another.
4.4 Transition
The transition toward future systems needs to be accomplished gradually. A Cost
Benefit Analysis should precede each step. The FANS II committee developed the
transition’s guidelines (ICAO, 2002). These encourage that the states introduce some of
CNS components early enough in order to get rapid return on investments. The
conventional and the new system will have to co-exist during the transition period to
ensure people become familiar and confident with the new technology before
completely relinquishing existing technology. The two systems will have to inter-
operate (interoperability). But the guidelines aim at minimizing this period to the
extent practicable. But because of great difference in the level of ATM in various parts
of the world and other factors that have to be taken into account, a reliable time frame
can not be specified. Basing the transition to CNS/ATM systems on improvements in
ATM and structural and procedural changes is ideal. Airspace reorganisation is
required.
Commercial factors are also crucial and investments in satellite based systems by
ANSPs need to match that of domestic and international customers. Moreover, integrity
of the air navigation systems must be maintained throughout the transition phase. Any
removal of existing navigation aids has to be done after consultations with the users.
Planning and implementation of improved ATM systems should also include
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consideration of training needs. The aviation community (Air operators, institutions and
service providers, manufacturers, states) have to cooperate to achieve these goals.
4.6 Affordability
With ICAO’s ATM Operational Concept and Global Air Navigation Plan, and IATA’s
ATM Implementation Roadmap, the airline industry has the potential to implement a
global airspace environment that will bring substantial operational and financial
benefits. However, implementing CNS/ATM systems will cost the industry money as
they will have to:
1) Upgrade aircraft avionics systems
2) Train the crews for the new systems and procedures
Progress towards the new systems have been slow. This lack of movement towards full
FANS implementation was not due to any particular technical problem, as the industry
effort had focused primarily on development of the technological case for CNS/ATM,
with many resulting competing technologies. The business case for CNS/ATM had
primarily been addressed at a cursory level, resulting in estimates of operational savings
without details on the benefit mechanisms. The ATM system must be considered as a
set of technologies; but it must also be considered as a business. The lack of
consideration of the economics of transition to the new operational concept has slowed
the pace of the implementation process (Allen et Al, 2005).
Airplane and ground system upgrades were slowed until they were confident that the
expenditures were justified. For an air carrier, a business case evaluation would include,
among other factors, assumptions about the impact on its costs of expected changes in
en-route charges and the impact on revenues of changes in air carrier fares and rates,
where these changes are associated with the implementation of CNS/ATM. These
impacts are in addition to the direct investment costs and operating cost savings
attributable to the new systems and identified in the cost/benefit analysis. The impact of
route charges will depend on the outcome of the policies and evaluations of the service
providers. Assumptions about fares and rates will reflect competitive pressures in air
travel and freight markets.
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Most of the basic practical guidance required relating to organizational options,
cost/benefit analysis, financial control, cost recovery and financing has been developed
following ICAO guidelines. The industry is confident that the new systems will bring
significant benefit to undertake such investments, and is participating to trials and
implementation programmes worldwide in collaboration with other industry’s
stakeholders (i.e. joint ASECNA and Air Afrique18 GNSS trials from 1994 to 2000).
For ASECNA, implementing new systems to improve the service will require
significant finance power. Between 2000 and 2010, installation and commissioning
amount to $US 276 million. This does not include interests on loans or depreciation. A
cost-benefit analysis for the 1995-2005 period shows investments of $US 235 million
including depreciation and interests. Expected incomes amount to $US 259 million,
essentially from air navigation charges. Airlines’ investments needs amount to $US 309
million. Expected comes amount to $US 341 million.
Big companies will be able to upgrade their fleet. But many small companies, which
own old fleet, will not be able to afford it. ASECNA will have to find adapted solutions
for them.
4.7 Conclusion
This chapter has allowed us to present the basic components of CNS/ATM systems.
How the proposed CNS/ATM technologies work, and how they actually deliver the
expected benefits to ASECNA has been studied. The study shows that the systems are
suitable to ASECNA as trials indicate that they could respond to its characteristics and
its problems. Satellite based navigation, data communication, and improved radar
surveillance, will render air traffic management much more efficient.
Future communication and satellite-based technologies will allow better exchanges
between pilots and controllers on both continental and oceanic airspaces. Trials
presented have shown that CPDLC, relying on high bit rates and more capacitive data
link techniques such as VDL, Mode S and satellite communication reduces
communication errors and reduce voice channels saturation and interferences. This
18 Before the airline’s bankruptcy
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means a safer communication environment. As controllers and pilots will loose less
time in unnecessary communications, this will have a positive effect on airspace
capacity, and increase safety margins. Moreover, controllers’ workload will
significantly been reduced, particularly in areas where traffic is relatively dense, which
will improve productivity and cost effectiveness in peak periods. In areas where traffic
is less dense, the new system will not have a significant impact, as controllers’
workload is already very low. At last, ATN will improve the quality, the speed and the
integrity of data transmission between users and service providers
Satellite navigation, in providing more navigation accuracy in conjunction with
augmentation systems, will allow aircraft to flight efficient trajectories and make a
better use of airspace with less dispersion, potentially avoiding diversion cost in bad
visibility conditions. Secondary airports will be accessed without the need of landing
aids. RNAV, RVSM, and RNP will increase route efficiency, safety, and capacity.
New surveillance technologies performance during trials (ADS, Radar Mode S) show
that aircraft detection and identification are improved in remote areas such as oceans or
deserts, and allow ANSPs to deliver a safer service at a significantly lower
acquisition and operating cost.
Big air operators are fitting their fleet with these capabilities. Small carriers will not
have the means to upgrade their old fleet. ASECNA has to adapt to each category’s
particular needs. At last, transition between the old and the new system requires
cooperation between the different stakeholders. To ensure a smooth shift in
technologies, interoperability between the systems is essential.
102
Chapter 5: Analysis of ASECNA’s Modernisation Strategy
The aim of this chapter is to present and analyse ASECNA’s modernisation strategy, for each CNS/ATM component.
5.1 Description
5.1.1 Communications
ASECNA’s objective is the full deployment of an ATN environment with the
possibility to accommodate FANS1/A and the highest degree of functionality possible.
Fixed Network: ASECNA has embarked in the modernization of AFTN by high-speed
links and in the integration of its telecommunication systems. The Interconnection of
sub-regional communication networks and the setting up of an independent satellite
digital telecommunication network within its area, for AFTN and mobile
communications needs and for exchanges of meteorological data to assist ATM are
being implemented.
Data Communication: The use of secured and efficient protocols is expected to
increase end-to-end reliability of data transmission. A Flight data automation program is
engaged: The FIR Antananarivo already has FDPS, CPDLC and ADS-C capabilities.
Trials for similar systems and testing of a VDL sub-network and HFDL are being
conducted in Dakar.
VHF coverage: The VHF coverage programme is well advanced. Plans suggest that
almost all ASECNA’s routes will be covered and controlled by means of VHF radio,
except the Oceanic FIR. VHF has been deported to Agades, Zinder, Tessalit, GAO,
Dirkou (FIR
Niamey- Areas of Routing 3-4-9), Faya-Largeau (FIR N’Djamena AR-3) by means of
VSAT stations. Others are being implemented in Bir Moghrein, Nema, Taoudennit,
Tombouctou, Nouadhbou (FIR Dakar continental, AR 1-9), Moroni, Toamassima,
Tolangnaro (FIR Antananarivo,AR-10), Sao Tome and Principe, Bria, Makokou and
Pointe Noire (FIR Brazzaville, AR-4-5). A program to modernise VHF and HF
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equipments and installation of VSAT TS Direct speech facilities in other places are
also on the way.
5.1.2 Navigation
Successful flight trials in May 2005 from Dakar to Nairobi have been conducted, using
EGNOS. These followed other trials in West and Central Africa, conducted in February
2003 in Dakar, Senegal and in June 2003 at many airports of the States of Central
Africa (Nigeria, Cameroon, Gabon and Equatorial Guinea). GNSS approach
procedures are already available for all major airports in ASECNA.
As it is necessary to maintain adequate navigation service during the transition period,
ASECNA has launched a program to replace Navaids (VOR, ILS, and DME…) in
certain locations before the full implementation of GNSS. The use of satellite
technologies has allowed the Agency to implement 21 RNAV routes over its upper
airspace since 2004.
RVSM are already implemented in Antananarivo, Brazzaville, Dakar, N’djamena and
Niamey’s Flight Information Regions in accordance with ICAO regional agreements.
Since the beginning of 2006, operators wishing to penetrate this airspace received
RVSM aircraft airworthiness and operational approval from the appropriate state
authority.
5.1.3 Surveillance
Voice position reports remain the dominant procedure. However in high and medium
traffic density terminals and approach areas, SSR will be required while ADS will be
progressively introduced.
ADS/CPDLC
Antananarivo’s and N’djamena’s FIRs have already implemented ADS/CPDLC.
ASECNA was the first to develop ground equipments in the AFI region for the ADS. It
served to demonstrate the potential advantages of ADS displays in the AFI region.
These were the first ADS trials on the continental scale.
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As part of a surveillance exercise, ASECNA is currently carrying out ADS/CPDLC
trials in Dakar. Implementation plan (2001-2005) provides for the installation of ADS
systems in Dakar and in Sal Island (cap Verde) to monitor the oceanic FIRs. These
systems have screen displays capabilities in order to monitor the aircraft position at the
control centres. The display technologies used are:
1. FPDS (Flight Data Processing System)
FPDS contains Flight Plan Air Situation Display – FPASD – that deliver a graphic
representation of flights not fitted with FANS1/A equipments. The system is capable of
managing both paper and electronic strips.
2. ADS
Any aircraft fitted with ADS is able to automatically exchange data with the ATS
system. The aim is to simplify the coordination between traffic adjacent control centres.
3. CPDLC
The system will use CPDLC data exchanged between pilots and controllers to
automatically update corresponding flight plans.
Trials were still on-going in June 2005. But regulatory and normalisation requirements
slow the decision process.
Radar Mode S
It is planned to install 5 Monopulse SSR mode S radars with full ADS/CPDLC
capabilities in N’djamena, Dakar, Niamey, Brazzaville. Abidjan’s radar is already
operational. They should all be operational within 2 years (2007). Trials are being
conducted in N’djamena, Dakar and Brazzaville. The new system will be able to
manage at least 17 airspace sectors simultaneously, and will permanently be monitored
by 12 controllers, including optional positions, instead of 5 today. A total of 24 to 30
controllers, forming teams of 4 to 5 people, will be trained in that purpose. Other
surveillance projects include multilateration surveillance systems at Bir Moghreim,
Taoudenit, Tessalit, Agadez Bria, and Faya Largeau.
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5.1.4 On-board the aircraft
The aircraft of major international airlines linking Africa to Europe are already
equipped with built-in onboard CNS/ATM systems. Aircraft only flying national or sub-
regional routes are equipped with RNAV-1 systems and autopilot. A low-cost
CNS/ATM system composed of a VHF data link, an ADS mode and GNSS for
navigation is added to it. Communications and ADS surveillance benefit from VHF
cover and ATM automation on the ground. These aircraft are to be equipped with a C-
mode transponder for surveillance radar requirements in some terminal regions. The
design approach for the configuration of avionics is modular, to allow the evolution
from one ATM level to another.
5.1.5 Aviation weather
To better meet the airline demands, ASECNA is integrating the requirements expressed
via IATA into its equipment plans. Over the period 2000-2006, ASECNA has
strengthened the capacities of its meteorological centres by making the following major
investments:
1. Renovation and upgrading of systems (digital barometers, satellite imagery
receiving stations, etc.), meteorological information distribution and visualization
systems and forecasting systems (SADIS, RADAR, SYNERGIE, etc.);
2. Installation of the two-directional SADIS link in Dakar (Senegal) to serve as back-
up to the AFTN for OPMET data exchange;
These systems have not all been implemented yet, but the process is well advanced.
ASECNA is progressively migrating onto the Second Generation Weather Satellites
(MSG), with greater capacity of data processing (Flight planning dossiers, Turbulence,
Obstacle…etc) (Ndobian Kitagoto, Met Engineer, ASECNA).
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5.1.6 Air Traffic Management
ASECNA’s ATM Concept is primarily instituted between airports rather than gate-to-
gate1. Departure/arrival management will be implemented through SIDs and STARs and
not through fully integrated management like in ECAC for instance. The airspace will
offer some flexibility sizing capability, whereas ECAC will implement a dynamic
flight-to-flight adjustment. The agency has also planned to offer its users their preferred
routes within the filed flight plans, with some collaborative decision-making between
aircrew and controller using ADS/CPDLC, instead of free flight with autonomous
operations. Three dimensional RNAV based on GNSS and RNP has been preferred to
full autonomous aircraft with airborne conflict avoidance and separation assurance.
Under an agreement with the ATM systems manufacturer Thalès, EUROCAT2 air
traffic management system is being installed in Dakar (Senegal), Abidjan (Ivory Coast),
Brazzaville (Congo) and in Niamey (Niger). The EUROCAT advanced air traffic
management system provides safe and efficient operations in high density, complex
airspace. Its operational displays, radar networks and flight plan processing comply
fully with ICAO standards requirements. It integrates radar, ADS-C, CPDLC and ADS-
B surveillance facilities for the management of traffic over oceanic and large continental
areas. It will provide area and approach air traffic control. There will be a combined
total of 28 working positions across all four centres which will provide controllers with
advanced flight plan and radar processing, and the capability for several centres within a
FIR to use a common and centralised database for improved co-ordination between
centres and for sharing and handing over of flight information, search for and resolution
of conflicts, flexible and dynamic track processing and ATN interface and Flight data
link service, especially for aeronautical weather.
1 Gate to Gate operational concept is based on better collaboration between ATM actors and better planning to enhance the exchange of accurate and reliable data, resulting into increased capacity and safety (Hugo de Jong & Marc Soumirant, june,1st,2004).
2 The Eurocat air traffic management system is a highly integrated air traffic management system, currently used operationally in more than 100 flight information regions. To date, 130 EUROCAT air traffic management systems, in multiple configurations, have been purchased by more than 50 civil aviation authorities all over the world.
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Airspace rationalisation
Within the framework of airspace rationalisation and controls extension, ASECNA,
plans to create 2 sectors within the upper airspace (>FL 245) in the Dakar continental
FIR, and integrate the existing UTAs.
The long term objective of ASECNA is to reform ATM procedures by reducing the
number of number of UIRs (upper flight data regions) and the number of FIRs and
control centres, harmonizing TMA limits and integrating of sub-regional ATM systems.
RVSM
In order to increase its airspace capacity, ASECNA has implemented RVSM in parts of
its airspace. RSVM implementation3 in ASECNA’s area comes after what was done in
the Oceanic FIR, and in the EUR/SAM corridor.
5.1.7 Cooperation
Technical aspects
ASECNA is cooperating with its neighbours within the framework of ICAO’s
CNS/ATM regional planning. Technical cooperation includes telecommunications, and
some aspects of airspace rationalisation. Main cooperation activities are done with
ENNA (Etablissement National de la Navigation Aerienne, Algerian ANSP) and
SADC (South African Development Cooperation) led by ATNS.
In the light of the drawbacks in the interface and the experience acquired, ASECNA
and ENNA have established an efficient and viable co-operation framework that could
enable them to carry out their mission of ensuring the security and regularity of air
traffic more efficiently. A master plan establishing a framework of cooperation has been
established since 2000. The aim of the master plan for coordination and
harmonisation context, is to tackle the scope and diversity of the problems caused by
the extension of the FIR interface under ASECNA and ENNA management, the
shortcomings in terms of communications, the volume of air traffic today and the
3 Between FL 290 and Fl 410 included. RVSM will be implemented with the upper lateral limits of the following UIRs: Antananarivo, Brazzaville, Dakar continental, Dakar Oceanic, N’djamena, Niamey, and SAL oceanic.
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envisioned growth, the application of the new ICAO civil aviation navigation system.
Ultimate goals are better coordination and harmonisation aiming at: harmonising
working procedures and methods; creating air routes; harmonising their means of co-
ordination; joint use of technical equipment; co-ordinating development activities and
exchanging information, particularly, with regard to CNS/ATM systems and the
exchange of personnel.
Considered as the appropriate framework for promoting the security and regularity of
air traffic, this plan which conforms to the ICAO recommendations will make it
possible to homogenise the levels of performance of the two systems.
Cooperation with SADC is well advanced. The interconnection of the SADC and
ASECNA VSAT networks allows Johannesburg to communicate with Congo
Brazzaville and Madagascar (Antananarivo) through the AFISNET4 network whilst
Antananarivo communicates with Beira (Mozambique) and Dar es Salaam (Tanzania)
through the SADC network. In ensuring a balanced solution, ATNS installed a SADC
terminal in Antananarivo and ASECNA installed the AFISNET terminal in
Johannesburg. The agency has migrated on Intelsat 10.02 with Nigeria, Ghana, and
other neighbouring Airspaces. It’s waiting for the others (CAFSAT, SADC) to join
them on the same satellite transponder.
Cooperation with Nigeria is very limited as this country has just started to build a
viable air navigation system. Nigerian Airspace Management agency (NAMA) was
created in 2000 following the Kenya Airways Airbus crash off the coast of Cote
d’Ivoire, killing 69 Nigerians on board, after it could not land in Lagos due to poor
visibility and the unavailability of instruments landing systems. The Agency has since
launched an ambitious modernisation programme and is cooperating with ASECNA
4 In view of the difficulty of developing a network on a landline infrastructure, the AFISNET West Africa sub-network is the first slice of this AFISNET aeronautical network developed by ASECNA. It is based on the installation of Earth stations sited directly on the major operating sites (airports, VHF remote antenna). The Earth stations of Bangui, Brazzaville, Douala, Libreville, and N'djamena have been in service since April 1995. The Dakar and Abidjan Earth stations have been in service since 1996. ASECNA operates and maintains the oldest and largest international satellite network dedicated to the needs of air navigation. The AFISNET network is composed of about fifty Earth stations, grouped into two sub-networks:
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which calibrates its Navaids equipments. Nevertheless, Nigerian airspace is developed
to meet domestic requirements.
Like in ASECNA, EUROCAT systems have already been planned elsewhere across
Africa including Nigeria, Sudan, Algeria, Egypt, South Africa and Mauritius. By
implementing similar systems each ANSP can benefit from a greater regional
interoperability and enhances the continent’s air safety. As ASECNA is the most
advanced form of air navigation integration, it’s calling for the others to adopt its
model, in order to deliver a seamless airspace.
The concept of “single African sky”
ASECNA and ATNS (South Africa Service Provider) jointly hosted African air
navigation service providers in Senegal in 2002 to discuss the challenges facing air
navigation in the region. The focus was on the benefits of regional service provision to
reduce duplication of services, the importance of the interoperability of systems, as well
as a continued drive for the commercialisation of air navigation service providers to
ensure that aviation revenue is reinvested into aviation (ATNS, 20002).
Within that framework, in 2003, in Yaoundé, Cameroon, ASECNA and other African
service providers agreed that the concept of a single African sky should be a long term
objective that needs to be studied. It should be the result of a gradual process
comprising the following steps:
1 Harmonisation of ATM systems and procedures, including training programs.
2 Rationalisation of service areas
3 Cross boundaries cooperation between ANSPs
4 Consolidation if necessary of air navigation services, based on costs-benefits,
the elimination of discontinuities, and the necessity of a flexible system taking
into account the users needs.
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5.1.8 Training
Seminar/workshops to raise awareness about CNS/ATM techniques are provided in the
region. ASECNA has introduced courses on the new systems into the training
programme for engineers and technicians in its training centres, with the participation of
the ICAO's TRAINAIR programme (established to encourage states to use standardised
training methodology, and develop international training systems sharing). An air traffic
management training centre for air traffic controllers will be installed at ASECNA’s
training school (EAMAC) in Niamey. Fitted with an ATM simulator, it will
significantly increase ASECNA’s ability to train its controllers and permits ASECNA to
standardise its training procedures and the qualification of its controllers. In order to
improve the quality of its services, ASECNA considerably increased its training budget
between 1998 and 2004 to meet the shortage of technical staff and put the required
number of staff in place. During that period, the number of technical staff increased
from 781 to 1,116 graduates. ASECNA has already trained controllers for the
introduction of RVSM although it is not implemented yet.
5.1.9 Financing
The principle of funding of the business case is that the planned CNS/ATM
technologies for ASECNA are economically viable investments with adequate financial
returns for both ASECNA and airlines.
The life cycle of the investment is assumed to be 15 years. The total capital investment
in this case can be fully recovered through the provision of user charges. The result of
this analysis indicates a life cycle net present value (NPV5) (i.e. present value revenues
minus present value costs) of $23.5 million. The payback period, the point at which
cumulative revenues equals cumulative expenses would be 12 years from the
implementation of the plan. Both CNS/ATM and current ground-based systems were
assumed to operate in parallel during this phase of the implementation.
5 The NPV approach requires predictions of the future profiles of the annual costs and benefits associated with the implementation of CNS/ATM systems. Once all the year-by-year expenditure and benefits are established, the net benefit (benefit minus cost) for each year are calculated and discounted back to the base year in accordance with standard accounting practices.
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Sources of Financing
ASECNA has signed financing convention with different financial institutions
worldwide and Political Organizations. These include the European Bank of
Investment, the African Development Fund, The West African Development Bank, The
Central African Bank of Development, The European Union and others.
CNS/ATM demonstrations and tests are generally self-financed and sometimes financed
by subsidies from these financing structures. For the actual implementation of the
system, the agency’s usual financers (mainly European and African) indicate that they
are ready to deal with and continue the adventure with ASECNA in upgrading its
equipment to the next generation.
Cost effectiveness sequencing
ASECNA’s current charging policy is as follows: Charge for use of en-route facilities
and services managed by the agency are payable whatever are the conditions in which
the flight is accomplished (IFR or VFR) and whatever are the departure and the
destination aerodrome. Charging varies depending on the nature of the flight (national,
regional, international) and the weight of the aircraft. However, these incremental costs
(A in the Figure 5.1) are unique to CNS/ATM systems, and would not be incurred if the
systems were not implemented (ICAO, 1995). In this later case, incremental
expenditures on present technology would be required in order to continue operating the
existing system (B in Figure 5.1). These would be avoided if CNS/ATM is fully
implemented. Substantial annual expenditures are common to current and future
systems (C in Figure 5.1). These expenditures would be incurred even if CNS/ATM is
implemented. CNS/ATM costs also comprise conversion costs (D in the Figure 5.1). In
the case of ASECNA, agency will have to pass these incremental costs to users as said
previously. This means that charges will progressively increase during the life cycle of
the investment (15 years), in order to reconcile current and future revenues and
capital expenditure. The investment program amounts for about $276 million dollars
from 1995 to 2010 (235 up to 2005). Assuming that a proportionate investment will be
consented during the following ten years, and that current and future systems coexist,
users will have to bear 225 million $US from 2005 to 2020, that is to say 16.5 million
dollars per year if a margin of 10 % is taken into account. ASECNA collected about 170
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million dollars in 2004. This means that the navigation charges could potentially
increased by 9.7 per cent per year over the period6.
Figure 5.1: Classification of Costs
Source: ICAO, 1995
5.1.10 ASECNA’s implementation schedule up to 2015
Step 1: 2005 to 2010
- Progressive removal of ground based systems that are necessary to
FANS systems: HF, NDBs, VORs, DMEs, ACARS, ILS/MLS Cat 1,
Radioborne… etc.
- Progressive introduction of CNS/ATM systems
- Participation to the end of global transition plan
Step 2: 2010 to 2015
- Transition completed and FANS systems are unique to be operated. The
plan will be updated according to the technologies available
6 The payback period may be different, and probably lesser, which will increase the annual rate
C
A
D
C
B
Cost
CNS/ATMImplementation
Existing system
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ASECNA is slightly late in its implementation plans. The removal of ground based
Navaids has not started. The Agency is even reinforcing ground based navigation in
some countries. However, this is consistent with the pace of global implementation.
5.2 Analysis
The strategy depicted above clearly shows that ASECNA is aiming at tackling three
operational aspects: Safety, Efficiency and Capacity. These objectives are in line with
the industry’s requirements that have been identified and defined earlier. In fact, the
agency is fully implementing ICAO’s CNS/ATM transition guidelines.
ASECNA’s high level strategic goal appears to be the consolidation and the
modernisation of existing systems, getting the future ready by gradually introducing
CNS/ATM systems that interoperate with the conventional means, in order to be
operational when these systems will be fully required.
For Communications, the strategy is to extend VHF coverage along international
major traffic flows and inhospitable areas. The modernisation of the
telecommunication network infrastructure and systems through digitalisation is a step
towards greater data transmission and processing accuracy, efficiency and capacity.
Recent deregulation of the telecommunication markets in the region is what allows
ASECNA to implement suitable systems for its operations.
For Navigation, the agency aims at ensuring the good maintenance of existing means
during the transition phase, establishing tests beds and technological survey for satellite
based navigation, and carrying-on the implementation of WG-84 coordinates. Once
completely introduced, satellite navigation will also be used in remote airports that
actually lack instrument landing means. It potentially concerns 76 secondary airports.
Depending on the quality of ground infrastructures, and the availability of practicable
runways, this will increase their availability for operations, and could create potentials
for air travel growth. Introducing RVSM in its airspace, the agency is permitting
homogenous navigation areas between EUR CAR/SAM, ASIA/PAC and ASECNA.
More than 90 per cent of Western airlines’ aircraft will be fitted with RNP and RNAV
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capabilities (as mentioned earlier in Chapter 4) by the beginning of next decade,
whereas local airlines could not have the means to upgrade their old fleet to that level.
Hence, ASECNA is adopting a modular approach by setting up flexible ATM systems
that will be able to cope with multiple aircraft navigation capabilities. By initiating
ADS-B trials for the Atlantic Antananarivo and Dakar’s FIRs, the agency is anticipating
traffic characteristics in the EUR/SAM corridor and the Indian Ocean.
This dual strategy will certainly respond to both the needs of large and small airlines,
but this is questionable, as it is clear that it could not be cost-efficient. The fleet of
certain national and sub-regional aircraft operators is heterogeneous, and they have
limited means. There are greatest concerns about their capacity to respect the
transition schedule. A well organized transition is costly in terms of regulations,
installation, testing and training for all of the means, on the ground and onboard. Badly
organized transition is even more expensive: maintaining dual ground and onboard
installations, delay in receipt of benefits.
Equally questionable is the ability of the agency’s strategy to deliver a fully efficient
navigation system. In fact, the strategy does not suggest a desire to totally cover the
airspace, but only the most frequented routes. The rigid routes structure being
maintained, it’s obvious that the benefits that could be derived from RNP and ADS
capabilities will significantly be limited in the continental airspace.
For Surveillance, ASECNA’s strategy is to progressively install modern surveillance
technologies such as SSR-Mode S and ADS/CPDLC in each one of its ACC and where
they are mostly needed for safety reasons.
For ATM, airspace rationalisation and cross boundaries operational harmonisation of
rules and procedures are the agency’s ultimate aims. But rationalisation is oriented
towards navigation efficiency rather than capacity in term of saturation. Cooperation
with other ANSPs is limited to technical collaboration and local operational
cooperation. Airspace redesign, as suggested by the project of a single African Sky,
similar to what is being studied in Europe through the Single European Sky initiative
(Functional Airspace Blocks) is probably for the very far term.
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For Weather, the plans are to follow technology evolution and to adapt the
infrastructure accordingly.
Finally, the pan African organization intends to finance its strategy through loans from
international finance establishments and appear to have the financial backing to reach
objectives.
Figure 5.2: Possible airspace redesign in 2030
Source: CANSO, 2005
The geographical distribution of new air navigation means suggests that the agency is
not anticipating a substantial growth of air travel domestic markets for the short or
medium term. City-pairs market is insignificant (as explained chapter 1) mainly between
Central and Western Africa. Moreover, local airlines have no interest in operating these
non profitable routes, and prefer to operate the gulf of guinea corridor to improve their
load factor. Therefore ASECNA’s strategy to concentrate on main regional and trans-
regional corridors actually responds to both local and western airlines’ needs.
5.3 Conclusion
ASECNA’s strategy is coherent with the region’s needs. The dual strategy perfectly
responds to the requirement to accommodate both big and small airlines. But the cost
effectiveness of this plan is questionable: Maintaining dual equipments is costly, and
will certainly impact users’ charges.
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Dakar’s ADS system programme is two years late for example and Brazzaville’s Radar
project is also late. It is difficult to predict whether or not the Agency will fully respect
its schedule. The success depends on many factors that are not directly under its control.
Partly because the implementation of new air traffic concepts requires that member
states update their legislations, which is often a long and slow process. Moreover the
lack of means in local airlines, and the high cost of upgrading their equipments also add
to the uncertainty. It is doubtful that CNS/ATM systems will have been fully
implemented by all stakeholders in ASECNA by 2010.
However, the time frame is similar to those of other countries worldwide, and the
implementation process is more or less at the same stage as other regions like Asia.
ASECNA is even more advanced than areas like Europe on some aspects of the
programme such as airspace integration since its airspace is already integrated.
117
Chapter 6: Recommendations and Conclusion
The primary objective of the thesis was to analyse the state of Air Navigation in
ASECNA area in order to find out regional needs and priorities, which responds to
the first research question. The study found that the needs are as follows.
1. Air traffic demand remains very low although the region’s economies are growing.
The growth is driving air travel demand. Moreover, real liberalization is looming,
based on the Yamoussoukro’s decision. Which is expected to boost the growth. But
that increased activity is observed on a restricted number of routes linking Europe to
main cities in ASECNA. These routes are operated by several carriers that dominate the
market.
Airlines can be divided into two groups: International airlines, and domestic carriers.
The first are mostly foreign carriers and are relatively healthy. They operate high yield
routes, possess young fleets and have a strong financial power. The second are mostly
domestic carriers, in a bad state. They operate low yield routes, their fleets are very old
and their have little financial margins. The region’s airline industry dramatically
needs to be supported by an efficient and a cost effective air navigation service to
help them to reduce their costs.
2. Fragmentation is limited in ASECNA’s airspace. The airspace is organised respond
to operational requirements. However, at a continental level, airspace is very
fragmented. Cooperation and harmonization are needed to avoid unnecessary
duplication of equipments, which is cost ineffective. The agency is leading the move
towards integration. More remains to be done to reach complete harmonisation,
particularly with the Nigerian interface.
3. Capacity appears not to be a real need in ASECNA as traffic is very low and the
airspace is very wide. But as the traffic is concentrated in a limited number of lucrative
routes, extra capacity is needed to keep efficient operations, and to maintain safety
margins in a context of growing traffic in these specific routes.
Chapter 6 Recommendations and Conclusion
118
4. Safety records are extremely poor in ASECNA. Relatively to the level of traffic, the
number of air proximities, runway incursions and accidents is high, and the agency is
often engaged. But what is more preoccupying is the way the agency manages these
problems. Given the results of investigations, it can be asserted that the agency does
not have a proper safety management system to systemically process and analyse
safety data. It is rudimentary for the least. The quality, quantity and consistency of
safety data are not adequate for managing safety. A review system should be
established, providing a clear severity classification and disseminating findings.
ASECNA needs to establish such a system if it wants to improve its safety records
and restore users’ confidence.
5. Inefficiency is mainly due to the use of conventional systems. These render the
system very rigid, with fixed routes. They have operational limitations that prevent the
optimal use of the available airspace which is costly to users. These systems also have
technical insufficiencies in term of communication, surveillance and air traffic
management that degrade safety records. The agency needs to upgrade its
infrastructure to deliver a service that responds to modern requirements, in term
of systems’ availability, and data quantity, quality and integrity.
6. Cost effectiveness is good in ASECNA when compared to Europe and the USA. But
given the high proportion of staff and superfluous expenditures, the performance can be
improved, by reducing unnecessary staff in some areas with very poor traffic. That
would help to raise controllers’ productivity, and decrease support costs.
The secondary objective of the thesis was to study CNS/ATM technologies and their
relevance to ASECNA region. It responds to the second research question.
Based on the region’s geographic characteristics, and its needs presented above, the
study found that the new systems brings better efficient, increases safety margins and
capacity, enhances data processing, and allows the extension of services. They will be
cost effective on the long term, as they will help to curb the maintenance costs, and
reduce airspace fragmentation as their implementation requires international
cooperation, and a substantial level of operational and technical harmonisation on the
continental level.
Chapter 6 Recommendations and Conclusion
119
The third objective was to analyse ASECNA’s on-going modernisation strategy, to
assess whether it will respond to the needs and the priorities highlighted. It responds to
the third research question.
The agency has technical objectives to improve the current system, and to implement
future air navigation systems. Some systems have already been installed, and others are
progressively being made available to users. But the agency is confronted to the need to
accommodate both small and big carriers which do not have common interests. Given
the predominance of foreign carriers and the necessity to assist local airlines to help
maintaining an acceptable level of air service within the region, ASECNA has decided
to put in place evolutionary new systems, allowing each type of carriers to upgrade its
fleet with regard to their means and their operations.
However, the segmentation of the agencies operating revenues being overwhelmingly in
favour of transcontinental activities, the agency has chosen to firstly and
progressively equip strategic areas of routing with CNS/ATM systems and concepts.
That responds to profitability imperatives. But it does not address the immediate safety
concerns all over its areas of responsibility particularly in remote regions. The agency
is not prioritising domestic markets where most accidents occur as most of
conventional systems are maintained there.
The airspace reorganisation process that is taking place will certainly reduce unit costs.
The introduction of new systems is also expected to reduce maintenance costs. But no
study measuring the economic impact of newly introduced systems is available for the
time being.
The users will have to bear the costly equipment upgrade, and will be passed the totality
of costs of acquiring, installing and operating CNS/ATM systems. In addition, the fact
that the agency is maintaining a dual system will inflate costs. The agency has planned
to increase navigation charges by 10 per cent increase per year. That is not a cost
effective sequencing given the general state of the airline industry. In particular,
navigation charges should not inflate as the result of the introduction of new systems
because it could have a negative impact on the local airline industry. Recent
agreements between the agency and IATA that have frozen navigation charges during
the past three years suggest that ASECNA is reconsidering its charging strategy. It
shows that the agency has adopted a pragmatic policy in the interest of its users.
Chapter 6 Recommendations and Conclusion
120
Despite limited delays in the implementation process, ASECNA has already done a
huge work to modernize its infrastructure and its procedures. Its strong financial
situation and the support of local governments and international financial institutions
guarantee that the agency will not lack means to carry on its programmes. However, the
slowness and the variability of legislation procedures and the fragmentation of
regulation authorities could generate additional delays. A key point in reaching its
objectives is how ASECNA will collaborate with states and civil aviation authorities to
speed up the process. Moreover, experts doubt that small local airlines will be able to
respect the schedule, which will delay the moment of benefits. Actually, the question is
not whether ASECNA will be able to deliver a modernised service and infrastructure to
match the needs; its local users and regional authorities constitute the real threat to the
programme.
The agency has a solid training policy, and is training air navigation staff in its own
schools to prepare the future and respond to the growing demand. That long term human
resource strategy guarantees the availability of sufficient skilled staff.
The agency cooperates with neighbouring air navigation service providers within the
framework of ICAO’s modernisation plans. A certain level of technical integration has
already been reached, in particular between ASECNA and South Africa. As the agency
is a leader in term of airspace integration on the continent, it’s coordinating
harmonization efforts.
To conclude, and in response to the main research question, it can be stated that the
ability of ASECNA to meet the needs of African Air navigation the 21st will depend on
the following key factors:
1. The respect of CNS/ATM systems’ implementation process.
2. The reconciliation of interests of major and small airlines.
3. The strengthening of ties with other African ANSPs.
4. The involvement and the commitment of member states and civil aviation
authorities.
5. And the availability of means to finance the modernisation programme
Chapter 6 Recommendations and Conclusion
121
ASECNA can help the Airline Industry reducing its costs through technology advances.
But will it be substantial? In fact, deep structural changes are required in airlines’
management practices in Africa. These necessary reforms, together with a real
liberalisation, could secure a consistent growth. Nevertheless, even deep structural
changes could only have limited impact if the demand side is not dealt with
appropriately. High air travel taxation is a common practice in the region. States should
revise that policy in the interest of economies.
Given that the programme is already well advanced, and taking into account the fact
that ASECNA’s top management is committed to modernize the agency, and to keep its
reputation as a leading and exemplary institution in Africa, it is highly probable that the
Pan African institution will make adequate technologies available to its users, although
there is no assurance that the time frame will be met. Whether states and air carriers will
be able to fulfil their obligations in term of regulations and equipments modernisation
remains uncertain. There are clear indications that they will not.
Limitations and Suggestions for further research
The contribution of this research was to give the reader an insight of an African region
rarely studied, and one of its leading organisations that tries despite numerous
environmental and structural constraints, to conduct a sound and successful strategy
towards modernisation.
However the work has several limitations. Many real-world problems were simplified
or ignored because their solutions were outside the scope of this research. Particularly,
political interferences in the management of the agency, non-harmonised civil aviation
regulations together with intrinsic social and cultural characteristics that definitely
influence the agency’s performances, are examples of research studies that could be
conducted by future students. However in a context of globalization and liberalization,
studying the impact of an hypothetic privatisation of ASECNA on the quality of service
would be a good contribution.
122
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APPENDIX 1: Presentation of ASECNA
History: An example of inter-African and Malgasy cooperation
“L’Agence pour la Sécurité et la navigation aérienne en Afrique et a Madagascar”
(ASECNA) was founded in 1959, in Senegal. It is a multinational organization,
created by 16 African countries1, 14 from Western and Central Africa, plus
Madagascar, and France. The group was joined by the Comorian Union in 2004. The
agency is presented as the best example of North to South cooperation, as well as the
structure for civil aviation excellence. ASECNA has managed to last more than half a
century because it adapted itself to the political economic context. When it was
created, ASECNA was mainly a cooperation organisation between France and
African French speaking countries and Madagascar. But years after it was founded,
the Malgasy and inter-African cooperation become Predominant. This transformation
was translated in the facts, by the transfer of the Agency’s head quarter from Paris
to Dakar, and by the “Africanisation” of the management. In 1974, the Dakar
convention was signed by the 15 countries (All the current members states, without
Equatorial Guinea who joined the organisation in 1987). The Dakar convention
remains opened to integrate any candidate country.
Mission: Air Navigation safety
ASECNA is governed by the Dakar convention, and essentially exercises community
activities in accordance with article number 2; but it also manages national
aeronautical activities, on a purely subsidiary basis, on the behalf of some individual
states and other organizations.
1 Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Comores, Congo, Equatorial Guinea, Ivory Cost, Gabon, Madagascar, Mali, Mauritania, Niger, Senegal, Togo.
127
Community activities
The agency controls an area 1.5 as large as Europe. This area is divided into 6 Flight
Information Regions (FIRs): Antananarivo, Brazzaville, Dakar Oceanic, Dakar
Terrestrial, Niamey, and N’Djamena2.
It ensures the Control of air navigation flows, aircraft guidance, the transmission of
technical and traffic messages, airborne information. It also gathers data, forecasts and
transmits aviation weather information. Theses services are applied for both en route,
terminal approach and landing phases of the flights.
ASECNA ensures terminal approach aids for the 25 main airports3 of the region, as
well as 76 secondary airports. This includes airports control, approach control, ground
aircraft guidance and movements, as well as radio aids and fire protection services.
For these reasons, ASECNA has the responsibility to maintain the equipments
necessary to deliver these services, a part from the runways.
National activities
Articles 10 and 12 of the Dakar Convention allow member states to entrust ASECNA
to manage, maintain and the install of aeronautical infrastructures. Benin,
Burkina, Central African Republic, Gabon, Equatorial Guinea, Mali, Senegal and
Chad signed specific contracts with the organization under article 10.
2 These cities are respectively the capitals of the following countries: Madagascar, Congo, Senegal, Niger and Chad. The Senegalese FIR is divided into an Oceanic FIR and a terrestrial FIR. 3
Douala, Port Gentil, Mahajanga, Garoua, Malabo, Bamako, Bangui, Ouagadougou, Gao, Brazzaville, Bobo-Diolasso, Niamey, Pointe Noire, Nouakchottt, Dakar, Abidjan, Nouadhibou, N’djamena, Cotonou, Toamasina, Sarh, Libreville, Ivato, Lome.
128
The Committee of Ministers
Commission for Accounts verification
The Board of Directors
General DirectionAccounting Agency Financial Control
Organisation and functioning
Statutory structures
Organization Chart
The Committee of Ministers, composed of member states’ transport or aviation
ministers defines the general policy of the agency. It meets at least once a year. The
Presidency of the committee is revolving on an annual basis, which constitute a
problem to the efficiency of the agency.
The Board of Directors takes necessary measures to ensure the well functioning of
the organization. But above all, it appoints the accounting agent, the commissioners
for accounts verification, and the financial controller.
External representations
In Each member state, the missions of the agency are ensured by a local
representation, organised as follows:
129
External representations organization chart
The agency also has two delegations, one in Paris, and the other in Montreal;
The one in Paris (DELP) ensures essentially missions for the general direction:
- Links with aviation administrations, airlines, international organizations;
- Air Navigation fees collection
- Aeronautical information edition
- Purchase and routing of equipments
The one in Montreal represents the agency in ICAO. The delegate is member of the
international organisation air navigation commission. He participates to the work of
the air navigation experts group, and has permanent links with the ASECNA’s
member states delegations in ICAO.
Financial
ASECNA resources are essentially derived from:
• Aeronautical fees (Landing and en-route)
• Member states contributions on their national activities entrust to ASECNA
• Loans from banks, institutions and states
The agency has posted remarkable operating and net results for years, and has always
been a profitable organization.
Representative
Air Navigation Operations Aviation Weather
Radio Electrical Infrastructure Civil Engineering Infrastructure
Administration and Finances Payment services
130
Appendix 2: Ground Based Navigation Systems Principles
1 How the VOR works
Each VOR operates on a radio frequency assigned to it between 108.0 megahertz
(MHz) and 117.95 MHz, which is in the VHF (very high frequency) range. The
channel width is 50 kHz. VHF was selected because it travels only in straight lines,
resisting bending due to atmospheric effects, thereby making angle measurements
accurate. However this also means that the signals do not operate "over the horizon",
VOR is line-of-sight only, limiting the operating radius to 100 mi (160 km).
VOR systems use the phase relationship between two 30 Hz signals to encode
direction. The main "carrier" signal is a simple AM tone broadcasting the identity of
the station in morse code. The second 30 Hz signal signal is FM modulated on a 9960
Hz subcarrier. The combined signal is fed to a highly directional antenna, which
rotates the signal at 30 times a second. Note that the transmitter need not be physically
rotating—all VOR beacons use a phased antenna array such that the signal is "rotated"
electronically.
When the signal is received in the aircraft, the FM signal is decoded from the sub
carrier and the frequency extracted. The two 30 Hz signals are then compared to
extract the phase difference between them. The phase difference is equal to the angle
of the antenna at the instant the signal was sent, thereby encoding the direction to the
station as the narrow beam washed over the receiver.
The phase difference is then mixed with a constant phase produced locally. This has
the effect of changing the angle. The result is then sent to an amplifier, the output of
which drives the signal pointers on a compass card. By changing the locally produced
phase, using a knob known as the Omni-Bearing Selector, or OBS, the pilot can zero
out the angle to a station. For instance, if the pilot wishes to fly at 90 degrees to a
station, the OBS mixes in a −90 phase, thereby making the indicator needle read zero
(centred) when the plane is flying at 90 degrees to the station (Wikipedia, ).
131
VOR station; Source: ATSEEA, 2005
132
2 How DME works
The DME system has a UHF transmitter/receiver (interrogator) in the aircraft and a
UHF receiver/transmitter (transponder) in the ground station. The interrogator transmits
interrogation pulses to the transponder, which in reply transmits a sequence of reply
pulses with a precise time delay. The DME receiver then searches for two pulses with
the correct time interval between them. Once the receiver is locked on, it has a narrower
window in which to look for the echoes and can retain lock. The time difference
between interrogation and reply is measured by the interrogator and translated into a
distance measurement which is displayed in the cockpit.
A typical DME transponder can provide concurrent distance information to about 100
aircraft. Above this limit the transponder avoids overload by limiting the gain of the
receiver. Replies to weaker more distant interrogations are ignored to lower the
transponder load.
DME frequencies are paired to VHF omnidirectional range (VOR) frequencies. So
generally a DME interrogator is designed to automatically tune to the corresponding
frequency when the colocated VOR is selected. An airplane’s DME interrogator uses
frequencies from 1025 to 1150 MHz. DME transponders transmit on a channel in the
962 to 1150 MHz range and receive on a corresponding channel between 962 to 1213
MHz. The band is divided into 126 channels for interrogation and 126 channels for
transponder replies. The interrogation and reply frequencies always differ by 63 MHz.
The channel width is 100 kHz.
One important thing to understand is that DME provides the physical distance from the
aircraft to the DME transponder. This distance is often referred to as 'slant range' and
depends trigonometrically upon both the altitude above the transponder and the ground
distance from it (Wikipedia, ).
133
3 How ILS works
The ILS stations are usually installed at airports which have full traffic. Today, ILS
stations are installed in almost all ASECNA’s international Airports. ILS is used to give
to the pilot, precision information when trying to land the aircraft.
The system’s reliability depends on equipments, the quality of installations and the
environmental conditions (mountains, buildings, climatologic conditions).
There are three categories of ILS as the table below present it:
Category
I
Permits a precision approach at an altitude up to 200 feets, above the ILS
Reference point. The ILS Reference point is located about 150 metres from
the aircraft touch down point.
Category
II
Permit a precision approach at an altitude up to 100 feets, above of the ILS
Reference point.
Category
III
Permit a precision approach at an altitude up to surface of the landing runway
with no Runway Visibility
ILS stations include the followed equipments:
Localizer
Localizer is a transmitter which gives information about azimuth with regard to the
Centre Line of the landing runway. Together with the glide slope transmitter (Glide
path), a precision approach can be performed.
The localizer antennas are located at the far end of the runway. They consist on a linear
array of multi-element antennas, with thick, staggered elements. Localizers transmit
between 108 and 118 MHz.
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Glide path
Glide path is a transmitter which gives information of the correct angle slope with
regard to the horizontal level of the straight of aircraft slide, during the landing. The
angle is 30.
ILS Marker Beacon and Compass Locator Stations
Marker Beacons are two or three transmitters which give information about the
precision approach, as control points for the aircraft, correct direction of the landing
runway extension. Marker beacons are VHF transmitters operating at 75 MHz. The
Outer Marker (OM) is used to indicate that an aircraft should intercept the glide path
when over the transmitter. The Middle Marker is used to indicate that the aircraft is at
the Decision Height (DH) for most approaches (Wikipedia, ).
4 Multilateration
A multilateration system consists of a number of antennas receiving a signal from an
aircraft and a central processing unit calculating the aircraft’s position from the time
difference of arrival (TDOA) of the signal at the different antennas.
The TDOA between two antennas corresponds, mathematically speaking, with a
hyperboloid (in 3D) on which the aircraft is located. When four antennas detect the
aircraft’s signal, it is possible to estimate the 3D-position of the aircraft by calculating
the intersection of the resulting hyperbolas.
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Source: (Roke Manor Research, August 2005)
When only three antennas are available, a 3D-position cannot be estimated directly, but
if the target altitude is known from another source (e.g. from Mode C or in an SMGCS
environment) then the target position can be calculated. This is usually referred to as a
2D solution. It should be noted that the use of barometric altitude (Mode C) can lead to
a less accurate position estimate of the target, since barometric altitude can differ
significantly from geometric height.
With more than four antennas, the extra information can be used to either verify the
correctness of the other measurements or to calculate an average position from all
measurement which should have an overall smaller error.
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Appendix 3: WGS-1984
Source: ASECNA 1996
In 1989, ICAO adopted WGS-84 as the standard geodetic reference system for
future navigation with respect to the international civil aviation. In 1994, ICAO adopted
Amendment 28 to Annex 15.
WGS 84 is an earth fixed global reference frame, including an earth model. It is defined
by a set of primary and secondary parameters:
The primary parameters define the shape of an earth ellipsoid, its angular
velocity, and the earth mass which is included in the ellipsoid reference
The secondary parameters define a detailed gravity model of the earth.
Since January 1st 1998, geographic coordinates (latitude and longitude) are published in
term of WGS-84 geodetic reference system. Geographic coordinate obtained through
conversion to the WGS-84 system but for which the degree of original accuracy
measured in the field does not meet the specifications of Annex 11 and Annex 14, are
pointed out by an asterisk. The degree of accuracy required for civil aviation is
determined as given in Annex 11.
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Appendix 4: ASECNA’S Telecommunications Network
138
Source: Boeing 2005 outlook
Appendix 5: Air Traffic Projected Growth by world region
139
Appendix 6 : ICAO’s Navigation SARPs
140
Appendix 7: ASECNA’s Satellite Navigation Circuits
141
Appendix 8 ASECNA’S ATS/Direct Speech Network
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APPENDIX 9: Introduction to CNS/ATM Systems
Drivers and Origins
Background
The air transport industry has grown dramatically and rapidly, more than other
industries during the last two decades of the 20th century according to ICAO. The
organization’s statistics show that from 1985 to 1995, world air passenger travel and air
freight respectively grew at an average annual pace of 5 and 7.6 per cent (ICAO, 2002).
The annual variations worldwide are shown by the figure below. The number of aircraft
departures gained almost 45 per cent from 1970 to 1995. A projected annual increase in
traffic between 1992 and 2010 estimated that traffic would increase by about 2.5 per
cent in North America, more 4 per cent in Europe, and 6 per cent in Asia, with the rest
of the world following the same trend (Gallotti , 1999).
Annual Changes in scheduled aircraft movements worldwide
Source: ICAO, 2002
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The picture below of a congested airspace best suggests how close some parts of the
world are to the gridlock. In some parts of Europe and North America, traffic is
restrained to preserve safety margins. Delays are growing, and this is hitting aircraft
operators’ bottom lines. On some days in the summer of 1999 European air traffic was
near to collapse. According to airlines’ representatives, delays have never been so bad,
at least not since 1959 (Spaeth, 1999, Para 2). IATA recently estimates that delays in
Europe have an annual cost of US$1.5 billion and 15 million minutes of unnecessary
flight.
instant traffic situation display over the US airspace.
Source: FAA, 2002
Elsewhere, in remote areas and over oceans, considerable improvements to ANS are
required, as the current technology has limitations. These are discussed in the next
chapter.
ICAO’s Global Implementation Plan and Monitoring
FANS Committees Work
Having considered the steady growth of international civil aviation before 1983, and
taking into account the projected growth at that time, the council of ICAO determined
in 1983 that conventional air navigation systems and procedures that were supporting
civil aviation were approaching their limits, and that time had come to develop new
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approaches that will better suite modern air transport exigencies. In that purpose, it
established a Special Committee on Future Air Navigation Systems (So called FANS
committee).
In 1989, the FANS committee concluded that new systems had to be developed to meet
the pace of air transport development worldwide. It had also established that the
shortcomings of conventional systems could have a negative impact on the
development of air navigation almost anywhere. It also recognised that the new
systems’ objectives should be to provide a cost-effective and efficient system adaptable
to all type of operations in as near four-dimensional freedom (space and time) as their
capability would permit. The committee recommended that this had to be done at a
global scale. In the wake of these conclusions, the ICAO council established a
committee in charge the monitoring and coordination of Development and transition
planning for FANS (So Called FANS committee II).
Tenth Air Navigation Conference
In 1991, the ICAO’s tenth Air Navigation Conference (AN-Conf/10 endorsed the
FANS concept, as proposed by the ad-hoc committees. The Conference concluded
(Recommendation 1/1 – Endorsement of the global ATM operational concept) that ICAO, the
States and the regional planning and implementation groups (PIRGs) consider the global ATM
operational concept as the common global framework to guide planning for implementation of
ATM systems and to focus all ATM work development.
Theses concepts eventually came to be known as the CNS/ATM systems. In 1993,
FANS II committee concluded that the implementation of these new technologies, and
their expected benefits had to be gradual. This meant that an action plan was needed, in
order to progress toward implementation of CNS/ATM technologies and systems. The
emphasized was put on the important role states and the regions had to play, through
PIRGs, with regard to the planning and implementation processes. The Planned
evolution of the process is as shown on the following figure.
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Evolution of CNS ATM implementation. Source: ICAO, 2002
The regional planning process
The regional planning process is ICAO’s main planning and implementation tool. A top
down approach is used, comprising a global guidance and regional harmonization
measures. This converges with the bottom-up approach formed by states and aircraft
operators and their proposals for implementation options.
Organizational and financial issues
The organizational and financial aspects in the implementation process of CNS/ATM
systems are the major challenges for the civil aviation community. Many CNS/ATM
systems are characterised by a multinational dimension, which requires an international
cooperation.
Developed states have the means to finance and develop their national CNS/ATM
plans. Australia is a good example. The implementation process is well advanced. But,
developing and poor countries (the majority of states), require assistance in many fields:
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- Needs assessments and project development
- Transition planning
- Financing arrangements
- Systems planning, specification, procurement, installation and
commissioning
- Human resource planning and development.
Legal issues
The legal framework that governs the conduct of service providers and users is the
Chicago Convention and its annexes. Many concerns are about the Global Navigation
satellite (GNSS) that shall be compatible with international law, including the Chicago
Convention, its annexes and all the relevant rules applicable to outer space activities.
Particularly, universal access to GNSS services without discrimination, the preservation
of states sovereignty, authority and responsibility. Aircraft operators and providers of
air navigation services rely on foreign systems, as the current GNSS facilities are
controlled by one or several states (USA, EU, Russian Federation).
The continuity of GNSS services is also a matter of concern among the community, as
the state provider could decide to stop them, and force the users to rely on inefficient
conventional backup systems.
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Appendix 10: Evolution of controllers Workforce from 2006 to 2011 in ASECNA
Centres WorkforceEnd 2005
Retirement2006
Forecastworkforce
(2-3)
Necessaryworkforce
(2007 – 2011)
Gap(4-5)
1 2 3 4 5 6Abidjan 26 0 26 35 -9Antananarivo 27 0 27 72 -45Bamako 24 0 24 35 -11Bangui 10 0 10 17 -7Bissau 7 0 7 9 -2Bobo Dioulasso
3 0 3 4 -1
Brazzaville 23 0 23 76 -53Cotonou 9 0 9 11 -2Dakar 42 0 42 104 -62Douala 23 0 23 35 -12Gao 0 0 0 4 -4Garoua 4 0 4 4 0Libreville 22 0 22 35 -13Lome 11 0 11 11 0Mahajanga 3 0 3 4 -1Malabo 8 0 8 11 -3Mopti 2 0 2 4 -2Moroni 7 0 7 11 -4Ndjamena 40 2 38 60 -22Niamey 33 0 33 76 -43Nouadhibou 5 0 5 8 -3Nouakchott 14 0 14 23 -9Ouagadougou 23 1 22 11 11Pointe Noire 6 0 6 11 -5Port Gentil 5 0 5 9 -4Sarh 2 0 2 4 -2Toamasina 4 0 4 4 0Yaoundé 8 0 8 11 -3Total 391 3 388 699 -
311
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