Yenneti Komalirani and Joshi Gauravkumar · 2010-11-22 · ist driving in the UK for a whole year.6 Th e report on ... aviation’s share would increase from about 1.6 per cent to

Introduction Air transport is an important marker of modern society and plays an integral role in the development of the economy. Since its advent in India in December 1912, the sector has witnessed 5 to 8 per cent growth in demand per annum. Aviation is a major contributor to the economic and social well-being of India, connecting it to the world as a trading nation, and fostering economic growth and prosperity. With the phenomenal growth1 of the sector, its environmental impact has also intensifi ed simultaneously. Aviation is increasingly being singled out as a major source of GHG emissions, a signifi cant contributor to global climate change, and a source of air pollutants. It has been said that one person fl ying in an airplane for one hour is responsible for the same GHG emissions as a typical Bangladeshi leading his life through a whole year (Beatrice Schell).2

Human-generated emissions at the Earth’s surface can be carried aloft and aff ect the global atmosphere. Th e unique property of aircraft is that they fl y several kilometers above the Earth’s surface. Th e eff ects of most aircraft emissions depends strongly on the fl ight altitude and whether aircraft fl y in the troposphere or stratosphere. Th e eff ects on the atmosphere can be markedly diff erent from the eff ects of the same emissions at ground level … Th e rate of growth in aviation CO2 emissions

Carbon Dioxide Emission Reduction Potential from Civil Aviation Sector

A Case Study of Delhi–Mumbai Air Route

Yenneti Komalirani and Joshi Gauravkumar

is faster than the underlying global rate of economic growth, so aviation’s contribution … to total emissions resulting from human activities is likely to grow in coming years.

—Intergovernmental Panel on Climate Change (IPCC)3

At present, domestic aviation is included in the sys-tem of national GHG inventories on which the Kyoto GHG reduction targets and the Climate Change Bill’s targets are based, but there is no agreed methodology as to how these should be assigned to individual countries. Against the background of signifi cant growth in air travel and aviation markets, and as a result of government and public focus on climate change and its consequences, air-lines are coming under increasing pressure to reduce their GHG emissions. An aircraft typically cruises at an altitude of 8 to 13 kilometres, where it releases several types of gases and par-ticles from fuel combustion, which alter the composition of the atmosphere and contribute to the climate change (Box 18.1). Th e impacts of gases emitted by the sector are captured in Table 18.1. According to IPCC, the contribution of CO2 is 2 per cent and NOx is 8 per cent of the global anthropogenic gases at present but will increase if the aviation sector

18

1 Two billion passengers have travelled by air in 2007 with 8 million out-bound passengers and 43 million domestic passengers in India according to ICAO (International Civil Aviation Organization). 2 Schell (2001). 3 IPCC (2000).

288 India Infrastructure Report 2010

continues to grow. Th e impact on global warming is expected to be more severe as the gases are released at higher altitudes. According to IPCC data, the transport sector accounts for 13 per cent of the total global GHG emissions out of which aviation accounts for 2 per cent (Figure 18.1). However, there are suffi cient uncertain-ties around these estimates to support conjectures that the impact may actually be much more. Currently, the estimates of emissions by the sector are estimated to be 1.48 billion tonnes by 2025, which exceeds the estimates made in 2004 by about 1.3 billion tonnes. Kenneth Button and Roger Stough4 review and assert that the

aviation emissions aff ect not only the environment but also the industry and society as a whole. Globally, the world’s 16,000 commercial jet aircraft generate more than 600 million tonnes of CO2, the world’s major GHG, per year. Indeed aviation generates nearly as much CO2 annually as that from all human activities in Africa (Aviation Environment Federation 2000).5

Even if you only fl y once a year you can generate a signifi cant amount of greenhouse pollution. For example a passenger taking a long haul fl ight from the UK to the USA can produce as much carbon dioxide as a motor-ist driving in the UK for a whole year.6 Th e report on ‘Aviation and global climate change’ of AEF, also says that for a typical journey under 500 kilometres, say London to Amsterdam, the amount of CO2 produced per passenger is 0.17 kilogram per kilometre for air travel, 0.14 kilogram per kilometre for travel by car; 0.052 kilogram per kilometre for rail and 0.047 kilogram per kilometre by boat.

Background on Aviation and GHG Emission ProjectionsAccording to IPCC’s summary of predictions of emissions,7 GHG emissions from the sector are slated to double by 2050 (Table 18.2). Due to this projected increase in emissions, the ‘radiative forcing’8 of aviation emissions may rise by a factor of 4–2 by 2050 over 1992.

Table 18.1 Gases Emitted from Aviation and their Impact on Atmosphere.

Gas Impact

CO2 Long-lived GHG. Contributes to global warmingO3 Lifetime weeks to months. Product of NOx emissions plus photochemistry. Th e eff ect of O3 is high at subsonic cruise

levels and causes radio-active reactions at those levelsCH4 Lifetime of ~10 years. Aircraft NOx destroys ambient CH4 H20 Th e eff ect is small because of its small addition to natural hydrological cycle. Triggers contrails, but actual contrail content

is from the atmosphereSulphate Scatters solar radiation to space. Impact is one of coolingSoot Absorbs solar radiation from space. Impact is one of warmingContrails Refl ect solar radiation, have cooling eff ect; but refl ect some infrared radiation down to earth, that has a warming eff ect; but

net eff ect is one of warmingCirrus Contrails can grow to larger cirrus clouds (contrail cirrus), which can be diffi cult to distinguish from natural cirrus.

Generally warming eff ects

Source: Federal Aviation Administration (2005).

Box 18.1How Does Aviation Contribute to Climate Change?

Aviation emissions arising from the combustion of kerosene include:

• Carbon dioxide (CO2);• Water vapour (H2O, which leads to the formation of

contrails and cirrus cloud at high altitudes);• Nitric oxide and nitrogen dioxide (or NOx, which forms

ozone, a GHG, at high altitudes);• Particulates (soot and sulphate particles); and• Other compounds including sulphur oxides, carbon

monoxide, hydrocarbons, and radicals such as hydroxyl.

Source: Federal Aviation Administration (2005).

4 Stough (2000). 5 Aviation Environment Federation (2000). 6 Refer to footnote 10. 7 IPCC (2000). http://www.grida.no/publications/other/ipcc%5Fsr/?src=/climate/ipcc/aviation/index.htm 8 Th e radiative forcing index is the measure of total eff ect of climate change. It is measured for Aviation as the ratio of total RF to that of CO2= (CO2+O3+CH4+H2O+contrails+Particles)/CO2.

A Case Study of Delhi–Mumbai Air Route 289

Table 18.2 Summary of Predictions of Emissions to 2015 and 2050

CO2 NOx

Average of estimates for 1992 476 MT 1.78 MTAverage of 2015 forecasts 1232 MT 4.04 MTPer cent of change 1992–2015 258 per cent 226 per centAverage of 2050 forecasts 2808 MT 7.33 MTper cent of change 1992–2015 227 per cent 181 per centPer cent of change 1992–2050 588 per cent 411 per cent

Source: IPCC (1999).

Th e International Energy Agency (IEA) in its World Energy Outlook 2006 forecasts the growth of transpor-tation and aviation fuel consumption and GHGs for the period of 2004 to 2030. Th e IEA provides two forecasts––the reference scenario and the alternative policy scenario. According to IEA, global transportation emissions are expected to increase by about 40 to 60 per cent depending on the assumptions made in each forecast (Table 18.3). Although the aviation sector is expected to grow more than the road sector (76 per cent to 91 per cent com-pared with 38 per cent to 53 per cent), aviation energy consumption is expected to still remain at 15 per cent of total transportation energy demand. GHG emissions from aviation would also remain at about 15 per cent of transportation GHG emissions (Table 18.3). Th e fl eet of aircraft is expected to grow more rapidly in non-OECD countries, especially in China, India, and Latin America. Global GHG emissions from the trans-port sector are expected to remain the same as today, at 14 per cent assuming BAU forecasts (Stern 2007). Th is implies that aviation’s share of global GHG emissions would remain the same, at least under the reference scenario. Under the many assumptions that the IEA has made regarding the alternative policy scenario, aviation’s share would increase from about 1.6 per cent to 3 per cent,

refl ecting the wider range of policies under consideration in other sectors. According to a study by Transport Canada, total revenue passenger-kilometres grew at an average annual growth rate of 4.3 per cent for all commercial air transport services between 1992 and 2004 (Table 18.4). By 2030, the Canadian aviation sector alone would account for 0.045 per cent of global GHG emissions, similar to today’s share. Boeing forecasts that the GHG emissions would grow to 33 Mt and account for 0.054 per cent of global GHG emissions as compared to about 0.043 per cent today. Airport Council International (ACI) forecasts that GHG emissions would grow to 27 Mt by 2030, an increase of 51 per cent. All the studies project substantial increase in GHG emissions from the sector and hence it is imperative that at least unnecessary emissions are avoided wherever feasible.

Aviation in India: the Delhi–Mumbai Connect

Indian aviation has experienced a revolution in the last fi ve years. Domestic traffi c has tripled, whereas the international traffi c has doubled. In fact as pointed out earlier, much of the projected increase in the global aviation sector is expected to come from expansion of the sector in developing countries such as India and China. According to Airports Council International pro-jections, India would be the third largest aviation market in the world by 2027 in terms of passengers handled (Table 18.5). Both policymaking as well as execution in the Indian aviation sector is still fairly weak on aspects driving eff ective reductions in GHG emission. Th is paper studies ways in which benefi ts of GHG emission reduction can be captured through improvements in operations. After careful study of the quantum of emissions, the possible airline strategies for dealing with this problem are assessed;

Table 18.3 Derived from IEA 2006, Mtoe refers to Megatonnes of Oil Equivalent

2004 2030 Percentage Percentage 2030 Percentage Percentage Ref. Scenario share increase Alternative share of increase of total 2004–2030 policy Total 2004–2030

Total Energy (Mtoe) 1,970 3,085 100 57 2,804 100 42Road 1,567 2,401 78 53 2,519 77 38Aviation 238 454 15 91 419 15 76Other 165 230 7 39 226 8 37 GHGs (Mt) 5,289 8,287 7,336

Source: IEA (2006).


at the next stage, sustainable, long-term solutions for airlines are identifi ed. Th is study focuses only on the commercial airlines (Civil IFR fl ights), which cover the ordinary passenger aircraft on the Delhi–Mumbai route.9

According to the data provided by the Offi cial Airline Guide (OAG) in September 2007 the Delhi–Mumbai route in India is the sixth busiest route in the world and the busiest route in India contributing to over 50 per cent of the total Indian air traffi c. It is said to be the third busiest route in Asia-Pacifi c after the Sydney–Melbourne route. Th e route also enjoys load factors between 75–80 per cent through the year.

Th e total distance from Delhi to Mumbai is 722 miles. Th is is equivalent to 1,163 kilometres or 628 nautical miles. Th e travel direction from Mumbai to Delhi is in the direction of the north (22 degrees from North). A typical fl ight between Mumbai and Delhi would have a fl ying time of about 1 hour 27 minutes. Th is assumes an average air speed for a commercial airliner of 500 mph, which is equivalent to 805 kilometres per hour or 434 knots. Th e exact fl ight time may vary depending on wind speeds. Estimates of Down to Earth10 show that the average fuel wastage per fl ight operating on this route is around 30–40 per cent. Th is route has over 40 fl ights that operate about 80 trips between Mumbai and Delhi every day. Each trip from Mumbai to Delhi is estimated to consume Aviation Turbine Fuel (ATF) to the tune of 4,500 kg. Apart from the ATF that is being used for a journey through the route, each plane has to carry 2,200 kg to 2,400 kg extra ATF to be consumed during the extra hour that the aircraft may have to hover over the destination airport waiting for run-ways and air-bridges to be cleared. Aviation fuel, which is a form of kerosene, produces about 2.158 kg of CO2 emis-sions per litre.11 In terms of emission, the 115,000 extra litres of fuel burnt every day between Delhi– Mumbai due to poor traffi c and congestion management translates to

Table 18.4 Canadian Aviation GHGs Forecasts (Mt)

Forecasts 2004 2030 Increase Share of global (in percent) GHGs in 2030 (in percent)

Transport Canada 18.2 39.4 116 0.065 ACI 18.2 27.5 51 0.045 Boeing 18.2 32.9 81 0.054

Sources: Derived from Canada Aviation & GHGes, Transport Canada.

Table 18.5 Growth of Aviation in India

2007 2012 2017 2027

Rank Country Passengers Rank Country Passengers Rank Country Passengers Rank Country Passengers (millions) (millions) (millions) (millions)

1 USA 1,450 1 USA 1,552 1 USA 1,790 1 USA 2,345

2 China 297 2 China 497 2 China 792 2 China 1,708

3 UK 243 3 UK 282 3 UK 324 3 India 581

4 Spain 210 4 Spain 251 4 Spain 294 4 UK 409

5 Japan 204 5 Japan 228 5 India 274 5 Brazil 407

6 Germany 186 6 Germany 218 6 Japan 259 6 Spain 370

7 France 140 7 India 176 7 Germany 252 7 Japan 330

8 Italy 129 8 France 168 8 Brazil 224 8 Germany 311

9 Brazil 120 9 Brazil 165 9 France 192 9 France 242

10 Canada 101 10 Italy 154 10 Italy 180 10 Italy 233

11 Australia 101 11 Australia 131 11 Australia 154 11 Australia 209

12 India 100 12 Canada 125 12 Canada 147 12 Mexico 206

Source: CAPA (2009).

9 Th e air traffi c is often divided into four categories: Civil IFR (Instrumental Flight Rules) fl ights; Civil VFR (Visual Flight Rules) fl ights, also called general aviation; Civil Helicopters; and Operational Military fl ights. 10 ‘Suspended Animation’, Down to Earth, 29 February 2008. 11 Greener by Design (2005).


248.2 tonnes of CO2 being pumped into the atmosphere, which is equivalent to the pollution caused by 161 small cars running for a year. In terms of costs, this wastes Rs 44 lakh per day as it costs Rs 1 lakh for a plane to hover an extra hour during a fl ight. Th ere are two diff erent types of traffi c on this route.

• Direct fl ights (Delhi–Mumbai)12

• Hopping or indirect fl ights (Delhi–X–Mumbai)13

Th ere were about eight airlines in operation in the study period in the route. Th ey are S2 (Jetlite), G8 (Go Air), IT (Kingfi sher), 6E (Indigo), 9W (Jet Airways), DN (Kingfi sher Red), and SG (Spice Jet).

Data Assumptions

• Traffi c data pertains to 2005–9 for the route (direct and via) and 2007–9 for other routes in the country.

• All the airlines are either departing from or arriving at the Delhi Airport (IGIL).

• Th ere are several other fl ights, which are moving on the route via diff erent cities. Some other fl ights continue after Mumbai. Th e fl ight routes mentioned below are fl ights departing from Delhi and travelling via other routes to Delhi or fl ights departing from Delhi and travelling through Mumbai to other places of the country, that is, all the fl ights considered have linkages through Delhi–Mumbai. Th e major hopping fl ight routes considered at the study period on this route are as mentioned below:

Composition of Routes

Direct Flights

Direct fl ights between Mumbai and Delhi at 77,357 greatly outnumbered the indirect fl ights at 16,124 in the period 2005–9 (Table 18.7). Table 18.8 shows the year-wise trends in direct fl ights on this route between 2005 and 2009. Th e number of

Table 18.6 Major Hopping Flights on Delhi –Mumbai Route

Departure Destination

Delhi–Ahmedabad–Mumbai (DEL–AMD–MUM)

Delhi–Bhubaneswar–Hyderabad–Mumbai (DEL–BBI–HYD–MUM)

Delhi–Vadodara–Mumbai (DEL–BDQ–MUM)

Delhi–Bhopal–Indore–Mumbai (DEL–BHO–IDR–MUM)

Delhi–Mumbai–Bangalore (DEL–MUM–BLR)

Delhi–Vadodara–Mumbai–Bangalore (DEL–BDQ–MUM–BLR)

Delhi–Hyderabad–Bangalore–Mumbai (DEL–HYD–BLR–MUM)

Delhi –Mumbai–Coimbatore–Kozhikode (DEL–MUM–CJB–CCJ)

Delhi –Mumbai–Cochin (DEL –MUM–COK)

Delhi–Chandigarh–Mumbai (DEL–IXC–MUM)

Delhi–Aurangabad–Mumbai (DEL–IXU–MUM)

Delhi–Jaipur–Mumbai (DEL–JAI–MUM)

Delhi –Mumbai–Chennai (DEL–MUM–MAA)

Delhi –Mumbai–Trivandrum (DEL–MUM–TRV)

Delhi–Jaipur–Udaipur–Mumbai (DEL–JAI–UDR–MUM)

Delhi–Chandigarh–Mumbai (DEL–IXC–MUM)

Delhi –Mumbai–Coimbatore (DEL–MUM–CJB)

Delhi–Udaipur–Mumbai (DEL–UDR–MUM)

Source: Analysed by the authors from data on fl ight details of Airports Authority of India (AAI) for the period 2005–9.

12 Th e direct fl ight is the fl ight travelling directly without any halt. 13 Indirect fl ight is the fl ight travelling via another city with a halt.


fl ights took a dip in the year 2007–8 and then almost trebled in 2008–9 over the previous year.

Indirect or Hopping Flights

Th ere are about 20 via routes covering the Delhi –Mumbai sector. Mumbai–Goa and Mumbai–Ahmedabad with 2,534 and 1,619 fl ights come second and third respectively to the Delhi–Mumbai connect in terms of traffi c (Figure 18.1). Indirect fl ights also witnessed a dip in 2007–8 followed by a steep increase in 2008–9 similar to trends in direct fl ights.

Comparison with Major Metros in India

Figure 18.2 shows that traffi c between Delhi and other major metros of India increased in 2008–9 over 2007–8. When compared with other metro pairs with arrival or destination being Delhi, it is clear that the Delhi–Mumbai route enjoyed a maximum of 42,256 fl ights

Table 18.7 Composition of Flights in the Study Route (2005–7)

Routes Arrivals Departtures Total

Delhi–Mumbai All Indirect Flights 6,942 9,181 16,124Delhi–Mumbai Direct Flights 24,821 52,536 77,357Total 31,763 61,717 93,481

Source: Analysed by the authors from data on fl ight details of the Airports Authority of India (AAI) for the period 2005–9.

Figure 18.1 Traffi c Growths on the Indirect Routes


Table 18.8 Year-wise Growth on the Route(Direct Flights)

Routes Total no. 2005–6 2006–7 2007–7 2008–9 of fl ights

MUM–DEL 77,357 13,681 18,573 12,745 34,703


25

220

322

3850

155

66130 150

320

12024

462522

308371

276

154

528

988

155 154

372462

154 154217

1057

308

636

727

210

319389 421

1546

91

696728

483

210

728

421

244

130

200

400

600

800

1,000

1,200

1,400

1,600

2005–6 2006–7 2007–8 2008–9

No.

offl

igh

ts

AM

D/M

UM

MU

M/H

YD

/BB

I

BD

Q/M

UM

BH

O/I

DR

/MU

M

BL

R/M

UM

BL

R/M

UM

/BD

Q

BL

R/C

JB/C

CJ

MU

M/C

OK

MU

M/G

OI

MU

M/H

YD

MU

M/I

XC

MU

M/I

XU

MU

M/J

AI

MU

M/M

AA

MU

M/T

RV

JAI

JAI/

UD

R/M

UM

JDH

/UD

R/M

UM

CJB

/MU

M–M

UM

/CJB

UD

R/M

UM

Route

Traffic Growth in the Via routes (2005–9)


during 2007–9. Delhi–Bangalore followed second with 26,562 fl ights.

Emissions Estimate for the Route

Exhaust emissions from aviation arise from the combus-tion of jet fuel (jet kerosene and jet gasoline) and aviation gasoline.14 Th ey arise during the two activities mainly, that is, during the Landing/Take-off (LTO) cycle and cruising (Figure 18.3).

• LTO cycle defi ned in ICAO (1993) includes all the activities of the aircraft near the airport that take place below the altitude of 3,000 feet (1,000 m). Th is therefore includes taxi-in and out, take-off , climb-out, and approach landing.

• Cruise is defi ned as all the activities of the aircraft at altitudes above 3,000 feet (1,000 m). Cruise, in the emis-

sion inventory methodology, includes climb to cruise altitude, cruise, and descent from cruise altitudes.

Exhaust emissions contain many gases apart from the GHGs which have potential of both warming as well as cooling, but a major proportion of the emission is CO2 (See Box 18.2). Emission calculations are based on the assumptions in Table 18.9. Th e growth rates for emission projection for 2025 are taken from two sources. In Scenario-1, the growth percentage is as per the Ministry of Civil Aviation, India (MoCA) and Scenario-2 is as per the GDP growth rate of the country multiplied with aviation elasticity of GDP growth. It is said that the aviation growth is expected to be twice that of the overall GDP growth rate (McKinsey Global Institute 2007).

Figure 18.2 Comparison of the Major Metros with the Route for the Period 2007–9


14 A fuel used only in small-piston engine aircraft, and which generally represents less than 1 per cent of the fuel used in aviation.

Route

2007–8 2008–9

12,821

7,516 7,687

5,5914,681 4,570

29,436

13,512

18,875

12,04910,892 10,441

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

DELHI–

MUMBAI

DELHI–

AHMEDABAD

DELHI–

BANGALORE

DELHI–

CHENNAI

DELHI–

HYDERABAD

DELHI–

KOLKATA

No.

offl

igh

ts

Traffic Growth in the Via Routes (2007–9)


CO2 is the major gas in the combustion with more than 60 per cent volume (See Figure 18.4). CO2 emission is calculated (See Box 18.3) for the study period for all the airlines for the routes (direct and indirect fl ights) (Table 18.10). CO2 has the maximum emission potential from the combustion process. Th e total CO2 produced for the considered period (2005–9) is about 5.62 million tonnes not considering the delays and other external factors. Th e Delhi–Mumbai route has the maximum number of fl ights and hence generates the maximum emission. All indirect fl ights were considered separately as emis-sions vary with fl ight paths and likely fuel consumption.

Figure 18.3 Standard Flying Cycles

Source: IPCC (1998).

Cruise

Clim

b

Descent

3,000 feet

(ca. 1,000 m)

Land

ingT

ake-off LTO-cycle

Taxi/idle Taxi/idle

Box 18.2 CO2 Emission Estimation Product of Kerosene Combustion

• Assuming a mean molecular formula of C12H23, 1 kg kerosene or ATF produces 3.156 kg CO2.

• CO2 is a long-life molecule with multiple lifetimes, depending upon sinks.• Th e Tier 1 approach for carbon-dioxide emissions uses the general equation;

ECO2 = ARfuel consumption × EFCO2

where:ECO2

= annual emission of CO2 for each of the LTO and cruise phases of domestic and international fl ightsARfuel consumption = activity rate by fuel consumption for each of the fl ight phases and triptypes EFCO2

= emission factor of CO2 for the respective fl ight phase and trip type

Source: IPCC Guidelines on National Greenhouse Gas Inventories. Reference Manual.

Th e emissions are calculated according to the assumptions mentioned in Table 18.9. Th e Delhi–Mumbai direct fl ights contributed most to the estimated emissions during the study period (2005–9). Th e CO2 emissions were estimated to be about 4.71 million tonnes for the period followed by NOx (2.53 million tonnes), N2O (0.48 million tonnes), and CH4 (0.12 million tonnes). It is estimated that the emissions were less in 2007–8 as the number of fl ights decreased (See Figure 18.5). Th e Delhi–Mumbai indirect fl ights were 16,124 during the period (2005–9). Th e estimated CO2 emissions were about 0.90 million tonnes for the period followed by


Table 18.9 Assumptions for Calculating Emissions

Assumptions

Fuel Consumption of Aircrafts Units ValueTotal Fuel Consumption for Airbus kg/hr Total Fuel Consumption for Boeing kg/hr Total Fuel Consumption for ATR kg/hr Total Fuel Consumption for CRJ2 kg/hr Average fuel consumption kg/hr

Emissions factors (IPCC,1996) Tier-1 CO2 CO2 e 19.5Tier-1 Nox CO2 e 10.5Tier-1 N2O CO2 e 2Tier-1 CH4 CO2 e 0.5

RFI 2.5

Growth rate for emissions projection (MoCA) Till 2015 growth % 12Till 2025 growth % 13Till 2050 growth % 15

Growth rate for emissions projection (GDP) Till 2015 growth % 12Till 2025 growth % 13Till 2050 growth % 15

According to McKinsey Global Institute GDP growth rate till 2005 % 6GDP Growth rate till 2025 % 7.3GDP Growth rate till 2050 % 7.3

Note: Th e assumptions as shown in Table 18.9 are taken from various sources as cited. Th e emission factors are considered for the Tier-1 method as the emission calculation is carried out by the Tier-1 method (IPCC 2006).Source: Assumptions of the authors based on the IPCC Reference Manual for Emission Factors, discussions with airlines for fuel consumption, McKinsey Global Institute and Ministry of Civil Aviation projections on the growth of the aviation sector for emis-sion projections.

Box 18.3 Tier-1 Method

Th e Tier-I method is the simplest method of IPCC methodologies (Tier-1: Purely fuel-based, Tier-2: Simple LTO cycle-based, Tier-3: detailed individual aircraft based) and is based on the aggregate fi gure of fuel consumption for aviation to be multiplied with average emission factors. Th e emission factors have been averaged over all fl ying phases based on an assumption that 10 per cent of the fuel is used in the LTO phase of the fl ight.

Emissions = Fuel Consumption * Average EmissionTh e following are the default emission factors:

CO2 : 19.5 tonnes C/PJ;CH4 : 0.5 kg/PJ, andN2O : 2 kg/PJ

Source: IPCC Guidelines on National Greenhouse Gas Inventories. Reference Manual.

Figure 18.4 Share of CO2 in the GHGs Produced

Note: Th e estimate of total CO2 produced is the sum for the period (2005–9).Source: Analysed by the authors from data on fl ight details of Airports Authority of India (AAI) for the period 2005–9.

NOx (0.48 million tonnes), N2O (0.09 million tonnes) and CH4 (0.02 million tonnes). But unlike the direct fl ights, indirect fl ights emissions were increasing (See Figure 18.6). Factoring in direct as well as indirect fl ights, the average emissions were estimated to be 61 tonnes CO2 e/fl ight, 33 tonnes CO2e/fl ight (NOx), 6 tonnes CO2e/fl ight (N2O) and 2 tonnes CO2e/fl ight (CH4) respectively. Both types of fl ights were used to project the emissions for 2050 on the route as well as to extrapolate for the country as a whole (See Figure 18.7).

GHG Emission Projections

Having estimated the emission levels on the route, we proceed to calculate GHG emission projections for the Delhi–Mumbai route. Th e emission projections were made to estimate the growth of the emissions on the route and for the sector in India in a Business as Usual scenario. For the projections, two scenarios were considered. • Growth of the sector according to the estimations of

the MoCA • Growth of the sector according to the growth of the

GDP growth (McKinsey Global Institute and Interna-tional Energy Agency)

60%32%

6% 2%

CO2Nox N O2 CH4

Total GHG Percentage


Figure 18.5 Delhi–Mumbai Direct Route Emission Growth Annually


Figure 18.6 Delhi–Mumbai Via Route Emissions Annually


0 500,000 1,000,000 1,500,000 2,000,000 2,500,000

Emissions in (T/Year)

2005–6

2006–7

2007–8

2008–9

833,677

1,131,810

776,648

2,114,723

CO2 Nox N O2 CH4

Route (Direct) GHG emissions

CO2 Nox N O2 CH4

39,88858,805

321,585

562,244

0

100,000

200,000

300,000

400,000

500,000

600,000

2005–6 2006–7 2007–8 2008–9

Em

issi

ons

in(T

/yea

r)

Route (Indirect) GHG emissions


Th e emissions shown in the particular year are for the year and are not cumulative. Th e scenarios are explained in detail as below:

Scenario-1: Growth Based on Estimations of the MoCA

In this scenario, the growth of the sector was based on growth estimations of MoCA—12 per cent till 2015, 13 per cent till 2025, and 15 per cent till 2050—for the aviation sector in India as a whole. In Scenario-1, the growth was extrapolated for the emission projections in 2050. Th e country-wide growth rate was assumed to hold for the Delhi–Mumbai route in this exercise, which may be an upward biased estimate as the two cities are already extensively served and the percentage increase may be less on this route. Th e emis-sions were calculated and projected for the route as a whole, not considering the direct and indirect fl ights separately. In this case, the projections suggest that, the emissions would increase from 2020, as the overall sector growth rate is expected to increase from 2020. It is esti-mated that the total emissions in 2030, 2040, and 2050 would be 28 million tonnes, 114.52 million tonnes, and 463 million tonnes respectively (See Figure 18.8).

Scenario-2: Growth of the Sector Based on GDP Growth Estimates of McKinsey Global Institute and IEA

In this scenario, the growth of the sector was calcu-lated based on of the expected growth the GDP of India as estimated by McKinsey Global Institute and IEA. McKinsey Global Institute and IEA estimate that the average annual GDP growth of India would be in the range of 6 per cent till 2015, 7.3 per cent till 2025, and 7.3 per cent till 2050. It is assumed that the aviation sector would grow at a rate that is twice the rate of growth of GDP of the country.15

Emission projections for Scenario-2 up to 2050 assume that the growth assumptions of GDP for India are appli-cable throughout the projection period upon emissions as well. Under this scenario, it is estimated that the GDP growth of India will stabilize after 2015 at 7.5 per cent per year till 2050 (as per IEA and McKinsey projections). In this case the analysis shows that the emissions will increase from 2020 as the overall sector growth rate tends to increase from 2020. Th e total emissions on the Delhi–Mumbai route will increase from 3.89 million tonnes in 2020 to 7.88 million

Figure 18.7 Annual Growth Rate of the GHG Emissions in the Route


15 According to International Air Transport Association (IATA 2008b).

CO2 Nox N O2 CH4 Expon. (Co )2

Overall GHG emissions

873,565

1,190,614

1,098,233

2,676,967

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

2005–6 2006–7 2007–8 2008–9

Em

issi

ons

in(T

/yea

r)


Figure 18.8 Emissions Projection of Delhi–Mumbai Direct Flights (Scenario-1)

Source: Analysed by the authors based on the civil aviation projections of the Ministry of Civil Aviation.

Figure 18.9 Emission Projections of Delhi–Mumbai Direct Flights (Scenario-2)

Note: It is said that Civil Aviation sector grows twice the GDP growth rate.Source: Analysed by the authors based on the GDP projections of India by McKinsey Global Institute.

Route GHG emissions

0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00

400.00

450.00

500.00

CO2 1.82 2.01 7.00 28.31 114.52 463.31

Nox 0.98 1.08 3.77 15.24 61.67 249.47

N O2 0.19 0.21 0.72 2.90 11.75 47.52

CH40.05 0.05 0.18 0.73 2.94 11.88

Em

issi

ons

in(T

/yea

r)

2009 2010 2020 2030 2040 2050

Route GHG emissions

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

CO21.82 1.92 3.89 7.88 15.93 32.24

Nox0.98 1.04 2.10 4.24 8.58 17.36

N O20.19 0.20 0.40 0.81 1.63 3.31

CH40.05 0.05 0.10 0.20 0.41 0.83

2009 2010 2020 2030 2040 2050

Em

issi

ons

in(T

/yea

r)


tonnes in 2030, 15.93 million tonnes in 2040, and 32.24 million tonnes in 2050 respectively (See Figure 18.9). Th e MoCA estimates prove to be much higher than that of McKinsey as the scenarios and assumptions were diff er-ent and hence the two projections are not comparable. But considering the fact that the sector is growing by leaps and bounds, any strategy proposed must provide long-term solutions.

Strategies for Emission Reduction Worldwide ‘Th e airline industry is in crisis. With a fuel bill of US$190 billion—one third of its costs—saving fuel is a matter of survival.’ (IATA 2007) Th e emission reduction options can be mainly catego-rized into:

• Technology Management• Operations Management• Economic Instruments

Th is section of the paper discusses the emission reduction strategies used internationally and proposes operational strategies, which can be implemented in Indian conditions and reduce the emissions in India signifi cantly. Mitigation measures to manage aviation emissions include changes in aircraft and engine technology, fuel, operational practices, besides regulatory and economic measures.16

• Aircraft and Engine Technology Options: Technol-ogy advances have substantially reduced emissions per passenger-kilometre. Research programmes address-ing NOx emissions from supersonic aircraft are also in progress. However, there is potential for further improvement. Any technological change involves bal-ancing across a range of environmental impacts. To be

seriously considered as a mitigation strategy, improved technology options must be both cost-competitive and off er signifi cant reductions in GHG emissions. Assum-ing that the emission reduction goals can be achieved through new technology, fl eet replacement worldwide with the new technology can take up to a decade. Several technological improvements exist to improve aircraft aerodynamics, such as applying laminar fl ow control (LFC) to an aircraft to reduce drag and, as a result, fuel consumption.17 More radical innovations include blended wing body aircraft that not only reduce drag but allow the entire aircraft to generate lift, as opposed to just the wings.18 More fuel-effi cient engines and incorporation of super-lightweight materials, such as fi bre-metal laminate, into the airframe off er additional avenues to improving aircraft effi ciency.19, 20

• Fuel Options: Although alternative fuels have lower net GHG emissions than traditional petroleum-based aircraft fuel,21 there are no practical alternatives to kerosene-based fuels for commercial jet aircrafts as in the near future. Biofuels, Fischer-Tropsch fuels,22 and liquid hydrogen could all present feasible alternatives in the future. Yet as with other sectors, alternative aviation fuels face numerous challenges with respect to their production, distribution, and cost, and it is not entirely clear what quantity of these fuels will be available and when, or what magnitude of GHG benefi ts can ultimately be achieved by using them (IPCC 2007). Additionally, to signifi cantly contribut-ing to GHG mitigation, the lifecycle carbon footprints of these fuels needs to be signifi cantly lower than the conventional fuels they replace. Jet aircraft require fuel with a high energy density, especially for long-haul fl ights and these alternative fuels like biofuel contain a low-energy-density which would be a limitation over jet fuels. Th e only feasible options for ‘drop-in’

16 IPCC (2000). 17 Laminar fl ow control (LFC) refers to technologies that modify the aircraft’s boundary layer (the layer of air that clings to the surface of the airframe). LFC increases fuel effi ciency by reducing turbulence in this layer. Th ere are two types of LFC technology: passive and hybrid. Passive LFC reduces aerodynamic drag by modifying the air-wing interaction through the shape of the front of the wing. Hybrid LFC removes a portion of the boundary layer (for example, through slotted or porous wing designs) to reduce drag. 18 Liebeck (2004). 19 Karagozian (2006). 20 Greener by Design (2005). 21 While the direct GHG emissions from combustion of biofuels or Fischer–Tropsch fuels will be similar to or the same as the direct GHG emissions from combustion of traditional petroleum-based aviation fuel, such alternative fuels can have signifi cantly lower net lifecycle GHG emissions since they can be manufactured from biomass feedstocks so that, in eff ect, combustion of such alternative fuels emits CO2 that was earlier absorbed from the atmosphere by the biomass feedstocks. 22 Fischer–Tropsch synthesis of transportation fuels involves gasifi cation of a carbon-containing feedstock (for example, biomass, coal) and production of a synthetic crude oil, which can then be processed into refi ned liquid fuel products.


replacements to petroleum-based jet fuels include hydroprocessed renewable jet fuel (HRJ)23 and Fischer–Tropsch (FT) fuels. Other fuel options, such as hydrogen, may become viable in the long term because these fuels do not present an immediate alter-native, and their adoption presents only in a long-term path towards lower carbon fl ight.

• Operational Options: Improvements in air traffi c management (ATM) and other operational procedures could drive 8 to 18 per cent reduction in aviation fuel burn. A large majority (6 to 12 per cent) of these reductions can come from ATM improvements, which are anticipated to be fully implemented in the next 20 years. All engine emissions will be reduced as a consequence.

• Regulatory, Economic, and Other Options: Although improvements in aircraft and engine technology and ATM effi ciency can bring some environmental benefi ts, these cannot fully off set the impact of the projected growth in aviation. Policy options to reduce emissions include more stringent aircraft engine emissions regu-lations, removal of subsidies and incentives that have negative environmental consequences, market-based options such as environmental levies (charges and taxes) and emissions trading, voluntary agreements, research programmes, and substitution of aviation by rail and coach. Most of these options would lead to increased airline costs and fares.

Operational Strategies Used Internationally

Cairns and Newson (2006) have showcased several ways of reducing aviation emissions based on improvement in operations. One of the key strategies prevalent internationally involves ATM aimed at reducing ineffi ciencies in fl ight patterns and encouraging fl ight patterns that take into account prevailing atmospheric conditions in order to minimize the impacts of non-CO2 emissions from aviation. It has been estimated that improvements in ATM could lead to increases in energy effi ciency, estimated to be in order of 6 to12 per cent (Cairns and Newson 2006; IPCC 1999). Th ree major international ATM initiatives have been identifi ed—A Single Sky for Europe; an effi cient

Pearl River Delta in China; and a Next Generation Air Traffi c System in the US (IATA 2007). Other improvements in operational effi ciency include:

• Increasing load factors;• Eliminating non-essential weight;• Optimizing aircraft speed;• Continuous Descent Approach• Limiting use of auxiliary power (for example, for heat-

ing and ventilation);• Reducing taxiing.

Operational Strategies under Consideration in India

Th ere are various measures for GHG emission reduction under consideration by various stakeholders of civil avia-tion like the DGCA, airlines etc. Th ese various measures are discussed here under.

• DGCA: Th e Directorate General of Civil Aviation (DGCA), the regulatory authority in India has set up an Aviation Environmental Unit to address problems faced by the sector and provide feasible solutions to the end-users. Th e unit has the responsibility of providing technical guidance on issues such as fuel conservation, emission reduction, and noise abatement. Th e unit is also conducting general awareness programmes for the people working in the aviation community through a lecture series. DGCA has also advised the airlines and air navigation service-providers to create environment cells in their respective organizations. Besides DGCA, the airlines, the air navigation agency, and others have also initiated measures aimed at improving fuel effi ciency and reducing emissions.

• Airlines: Th e airline operators always have incentives to bring about improvements in fuel effi ciency of their respective fl eets. Th ey have already started targeting reduction in fuel consumption by adopting better operational procedures such as minimum usage of Auxilary Power Units (APU),24 reduced fl ap take-off and landings, idle reverse on landing, proper fl ight planning system, adhering to proper maintenance of aircraft, weight reductions in cabin equipment, cater-ing services, avoiding carrying extra fuel on board, etc. Similar exercises are being adopted towards noise

23 Hydroprocessing plant- or animal-based oil is similar to the process of conventional crude oil refi ning. First, the oil is ‘hydrotreated’ by adding hydrogen, which increases the oil’s hydrogen-to-carton ratio. Th en, the molecules that result are ‘cracked’, yielding a fi nished jet fuel product. 24 Th e primary purpose of an aircraft APU is to provide power to start the main engines. It is a small engine, situated at the base of the tail of a plane (in most cases) that can be turned on if ground support is not off ered. Th e APU is also used to start the engines of the plane as this requires a great, sudden burst of power which, in some cases, the standard battery alone cannot supply.


abatement in terms of minimum usage of thrust reversal, low-noise low drag approaches, steep climbing during take-off , etc. Airlines are also advised to develop Balanced Approach Procedures for minimizing noise during landing. Th e fuel effi ciency litres/Revenue Tonne Kilometres (RTK) data from airlines operat-ing at international sectors have been collected and analysed. Airlines are working to bring the current fuel effi ciency of their fl eet close to world average (ICAO 2009a).

• Air Navigation Service-provider (ANS): Consistent high growth rate of civil aviation in India coupled with the emergence of new airlines with fl eets of new generation aircraft has necessitated rapid up-gradation of facilities, procedures, and infrastructure at all airports. Th e ANS are also contributing to this national endeavour through implementation of Performance-based Navigation (PBN) procedures for optimizing airspace utilization and enhancing airport capacity by taking advantage of airborne capabilities and Global Navigation Satellite Systems (GNSS) (ICAO 2008). PBN represents a shift from sensor-based to performance-based navigation. It specifi es performance parameters in terms of accuracy, integrity, availability, continuity, and functionality in the context of a particular airspace and aircraft Area Navigation (RNAV) system. RNAV can be defi ned as a method of navigation that permits aircraft operations on any desired course within the coverage of station-referenced navigation signals or within the limits of a self-contained system capability, or a combination of these. Performance requirements are identifi ed in navi-gation specifi cations, which also defi ne the choice of navigation sensors and equipment that may be used to meet the performance requirements. Th e development of the PBN recognizes that advanced aircraft RNAV systems are achieving a predictable level of navigation performance accuracy which, together with an appro-priate level of functionality, allows a more effi cient use of available airspace (ICAO 2010). For sustained eff ort in implementing PBN procedures at all airports and airspace in India, a PBN Implementation Roadmap of India has been established with the objective to accrue quantifi able benefi ts to the stakeholders in

terms of fuel savings, reduction in emissions, capa-city enhancement, and improved access to the airport. PBN RNAV-1 Standard Instrument Departures (SIDs)25 and Standard Terminal Arrival Routes (STARs)26 have been made operational at Mumbai, Delhi, and Ahmedabad airports since August 2008.27 PBN RNAV-1 SIDs and STARs have been developed by AAI-India with the assistance of Mitre for Chennai and Hyderabad and have been operational since 2009. Th e implementation of PBN at these airports has reduced the fl ight distance (Great Circle Distance) leading to reduction in annual fuel consumption. Th is reduction in fuel consumption has reduced the quantity of carbon emissions. Further, plans for implementing Continuous Descent Approach (CDA) at major airports of India are under consideration (ICAO 2009b).

• International Air Traffi c Association (IATA): More effi cient operations with regard to fuel conservation can save up to 6 per cent according to IPCC. Ineffi -ciency in the ATC can add 12 per cent to 18 per cent in fuel bills and IATA estimates that within India, a streamlined ATM system can cut airlines’ fuel bills and thus emissions by more than 50 per cent. IATA pub-lishes best-practice guidelines and its Green Team is advising carriers on implementation. Airlines are trying to reduce weight by removing items such as in-fl ight magazines, pillows, and blankets; more regular cleaning and in the case of Japan Airlines, encouraging passen-gers to visit the bathroom just prior to boarding (IATA 2008). According to IATA estimates in 2005, adopting such measures could have reduced 11 million tonnes in emissions by 2008.

Operational Strategies Proposed for IndiaAfter studying the various operational strategies available globally and under consideration in India, the following operational strategies have been proposed for India as it is found that these strategies are viable economics and in applicability. Th e emission reduction potential has also been studied by adopting these strategies for the Delhi–Mumbai air route.

25 A SID, or Standard Instrument Departure, defi nes a pathway out of an airport and onto the airway structure. A SID is sometimes called a Departure Procedure (DP). SIDs are unique to the associated airport. 26 A STAR, or Standard Terminal Arrival Route (‘Standard Instrument Arrival’ in the UK) defi nes a pathway into an airport from the airway structure. STARs can be associated with more than one arrival airport, which can occur when two or more airports are in close proximity (for example, San Francisco and San Jose). 27 SIDs and STARs are procedures and checkpoints used to enter and leave the airway system by aircraft operating on IFR fl ight plans. Th ere is a defi ned transition point at which an airway and a SID intersect.


Continuous Descent Approach (CDA)

For approaches into busy airports, stepwise descent profi les are standard practices. However, it is recognized that the CDA allows considerable fuel savings (with associated reductions in CO2 emissions). In addition, the noise footprint is considerably reduced and the chances of encountering a wake vortex from another approach-ing aircraft are reduced. In this the aircraft, instead of descending using the conventional step method, descends from a high altitude moving towards the ground steadily (See Figure 18.10). When the aircraft uses the stepped approach, it joins ‘stacks’28 at diff erent levels. Th e CDA method removes the need for stacks, and therefore reduces the chances of the aircraft encountering wake vortices from other approaching aircraft. About 300–1,000 pounds (135–450 kg) of fuel can be saved per fl ight per landing or 1 tonne of CO2 and further reducing noise and emissions further.29 For diff erent kinds of aircraft, the saving potential varies. For example: CDA saves—for a Boeing B-767 around 165 kg fuel or 525 kg CO2 per arrival. CDA also reduces nitrogen oxides (NOx) pollutants by 30 per cent at 3,000 feet and below. Figures 18.6 and 18.7 depict CDA (green fl ight path) and stepped approach (red fl ight path) graphically. Th e table below (Table 18.10) shows the amount of fuel saved by applying CDA in the Delhi and Mumbai

airports. Th e fuel saved is thus from the Delhi–Mumbai routes on the basis of actual fuel used and emissions calculated in the route. Some instances of successful implementation of CDA are presented below.

• Louisville International Airport in Kentucky: At Louisville International Airport in Kentucky (Clarke et al. 2004), it was found that noise in the proximity of the airport dropped between 3.9 and 6.5 decibels with the use of CDA as opposed to the stepped approach.

• Mather Airport, Sacramento County Airport System:Noise produced by Boeing 757 and Boeing 767 ap-proaching the airport was measured prior to, during, and after the implementation of the CDA (ESA 2006). Th e results are presented in Tables 18.11 and 18.12.

CDA signifi cantly reduced aircraft noise levels on a single-event basis as UPS’s30 Boeing 757 aircraft approached Mather Airport. Th e average reduction at each of the measurement sites was a palpable 4 decibels. Th e reduction in noise levels (again on a single event basis) for the ABX’s Boeing 767 during CDA was not as consistent as the UPS 757, but that is to be expected as the ABX’s CDA is in the early stages of development and implemen-tation. Noise reduction is a good indirect measure of fuel

28 Normally an altitude of 6,000 or 7,000 feet. Stack basically mean altitudes in aviation terms 29 FAA Flight Plan. Washington DC: Th e Federal Aviation Administration. FAA (2008). 30 United Parcel Service.

Figure 18.10 Continuous Descent Approach Method

Source: Air Transport Association, European Air Traffi c Management.

ConventionalapproachFuel used for enginetrust at eachlevelling

A Different Approach

.

The conventional star-stepped approach used by pilots today involves

descending in steps Using engine thrust to level off in a continuous

descent approach, or CDA, a pilot keeps the plane at cruising

attitude until it's near the airport. Then, depending on the

airport, the pilot, with engines idling decends straight

to the runway, or near the runway where he

completes the landing in the traditional manner.

With CDA, planes burn less fuel and

reduce emissions and noise.

ContinuousDescentApproach


effi ciency and is desirable by itself to reduce noise pollu-tion in areas close to the airport.

• CDA at Schiphol Airport, Amsterdam: CDA has been in use at Schiphol Airport, Amsterdam during night hours on a single runway for some time now. Th e National Aerospace Laboratory of France stud-ied FMS31 data of actual fl ights on Boeing 747–400

and Boeing 737–300/400 2000 to compare CDA procedures with conventional procedures to demon-strate the substantial environmental benefi ts of the CDA. Noise footprints (65 dB(A)) were found to be 30–55 per cent smaller (about 30 sq. km for B747 and 15 sq. km for B-737). Fuel consumption during the last 45 kilometres of the fl ight was about 25–40 per cent lower (approximately 400 kg for B-747 and 55 kg for B-737).

Diff erences were found to be mainly due to the presence of a horizontal segment in conventional approaches. Conventional 3,000-ft approaches in general show larger fuel consumption when compared to 2,000-ft approaches with equal length of the horizontal segment. Th is is mainly caused by the diff erence in Instrument Landing System (ILS)32 fl ight path length. Noise areas for 3,000-ft approaches are in general smaller than for 2,000-ft approaches at comparable horizontal segment lengths. Despite the longer distance with higher thrust settings along the ILS glide slope, the higher altitude seems to over-compensate for this unfavourable eff ect.

Implementing CDA in India

Th ere is an easy way to implement CDA today––it is a simple clearance by ATC33 instructing individual fl ights to ‘descend and maintain [assigned altitude] at the pilot’s discretion’ in a way that does not force the aircraft to level

Table 18.10 Emission Reduction Potential and Fuel Saving through CDA for the Delhi–Mumbai Air Route

2005–6 2006–7 2007–8 2008–9

Fuel effi ciency by continuous descent arrival (kg) 22,392,114 31,949,497 21,122,127 48,495,104Reduction of cost of fuel after continuous descent approval (million USD) 15,249 23,962 19,538 33,025CO2 emission reduction potential (T) 1,091,616 1,557,538 1,029,704 2,364,136Total CO2 emission reduction (T) 109,327 155,990 103,127 236,772Total cost of fuel saving (million US$) 1,527 2,400 1,957 3,308

Note: Cost of total fuel saved (million $) 9,191Total CERs generated(T) 605,216@’ price of 13$/T $ generated 7,858,734@’ price of 13$/T million $ generated 8Th e CER price of 13$/T is taken as of the January 2009 price.Source: Analysed by the authors from the example of Boeing B-767 provided above in the text.

31 Th e Flight Management System is a specialized computer system that automates a wide variety of in-fl ight tasks, reducing the workload on the fl ight crew to the point that modern aircraft no longer carry fl ight engineers or navigators. 32 An instrument landing system (ILS) is a ground-based instrument approach system that provides precision guidance to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, high-intensity lighting arrays to enable a safe landing during instrument meteorological conditions (IMC), such as low ceilings or reduced visibility due to fog, rain, or blowing snow. 33 Air Traffi c Control.

Table 18.11 Number of CDA and Non-CDA UPS Boeing 757 Aircraft Arrival Noise Events

Site No. Non-CDA CDA Total

1 52 38 902 70 41 1113 67 33 1004 74 34 108

Source: ESA (2006).

Table 18.12 Number of CDA and Non-CDA UPS Boeing 767 Aircraft Arrival Noise Events

Site No. Non-CDA CDA Total

1 22 8 302 30 7 373 34 7 414 40 7 47

Source: ESA (2006).


off at an interim altitude assignment. Th is will allow the pilot to start descent at the profi le that is optimal for fuel savings. Although there are huge environmental benefi ts of the CDA, it should be noted that for the introduction of CDA in daytime operations, improved ATC concepts are necessary in order to satisfy, or even increase, the present day approach capacity of conventional procedures.

Optimizing Routes and Air Traffi c

Required Navigation Performance (RNP) is a type of Per-formance Based Navigation (PBN)34 system that allows an aircraft to fl y a specifi c path between two three-dimensionally defi ned points in space (See Figure 18.11). Global ATC community devised this system to increase ATC’s capacity to handle the anticipated demand of the traffi c along with airspace user requests to reduce fl ight time and save money. Th is can be useful for en route descents, terminal manoeuvring areas, and fi nal approach-es where the systems would speed schedules and fl ying times according to prevailing winds. RNP can assist in aircrafts’ approach and departure procedures in busy airports. It can reduce delays resulting from shorter arrivals for RNP aircraft. It also maximizes use of the onboard navigational capability of the mod-ern aircrafts. Integration of RNP into the ATM system provides greater fl exibility to balance operational require-ment with community expectations. RNP also facilitates a CDA. Non-RNP fl ights following an RNP aircraft benefi t from reduced delays derived from the shorter RNP approach. In response to the growing demands, the

International Civil Aviation Organization (ICAO) has specifi ed that RNP is an essential element of communi-cations navigation surveillance/air traffi c management (CNS/ATM) and is encouraging early implementation in the en route environment. Th e Brisbane Green Project with an RNP has saved 650,000 kg of CO2 emissions in the fi rst year alone with a fuel saving of 200,000 kg for a year. Th e total number of track miles saved during Stage1 is estimated to exceed 17,300 nautical miles. Th e RNP path ensures that the low-level fi nal approach is conducted over the river and industrial areas. It also ensures increased safety in all weather conditions. By optimized routes systems, the aircraft can become 12 per cent more fuel-effi cient (Brisbane Green Project 2007).

Introducing RNP in India

Th e following enhancements would reduce the fuel sig-nifi cantly, further minimizing the costs and emissions (See Table 18.13). Enhancements to the Air Traffi c Management and Air Navigation Systems:

• More fuel-effi cient approaches and overall routing• Reduced vertical and horizontal separation minima—

expanding available airspace through tighter spacing, thus giving airlines a greater choice among fuel-effi cient routes and altitudes.

Improving Air Traffic Management (ATM) to Reduce Delays in IndiaAs mentioned earlier, India suff ers serious lacunae in its operational management system; per day cost of poor ATM on the Delhi–Mumbai route could be of the order of INR 44 lakh.35 Clearly, there is ample scope for improve-ment. After studying the existing operational measures under consideration in India for Air Traffi c management, it is found that proper ATM can have a great impact in reducing the delays and further saving the fuel used, emissions, and the cost incurred in the delays. Table 18.14 presents information on delays on the Delhi–Mumbai route in a day (2008–9). Th e fi gures are based on calculations, the methodology for which has been explained earlier. According to the analysis, there are about 80 fl ights a day on this route. Around 40 of these 80 fl ights are in the air during peak hours. Considering that peak hour fl ights are usually delayed by half an hour, it is apparent that

34 PBN system is explained under the Air Navigation Service-provider Section of the measures under consideration. 35 ‘Suspended Animation’, Down to Earth, 29 February 2008.

Figure 18.11 RNP Approach Shows System

Source: Brisbane Green Project 2007.


916 tonnes of CO2 emission can also be prevented per day by optimizing the delays in the route.

Other Measures

Apart from the above mentioned measures, a few other measures are also proposed which have to be studies in detail for their applicability for Indian conditions. Th e measures are as explained below:

• Flex Tracks, User Preferred Routes (UPRs), Dynamic Re-routes:– Flex tracks permit air-carriers to make the best use

of tailwinds or avoid headwinds in fl ight planning. Flex tracks challenge the ATC system each day with widely varying routes, but the savings for airlines are enormous. Th e initiative came out of the Australian Air Traffi c Management Strategic Plan issued in 2002 as part of the country’s commit-ment to implementation of ICAO’s global plan for future ATM.

– UPRs are customer designed for each individual fl ight in order to meet the specifi c needs of the aircraft for that fl ight, including fuel optimization, cost-index performance, or military mission require-ments. UPRs are calculated based on factors such

Table 18.13 Emission Reduction Potential and Fuel Savings by the RNP for the Delhi–Mumbai Air Route

2005–6 2006–7 2007–8 2008–9

Fuel effi ciency by optimizing routes and air traffi c (kg) 21,678,556 30,931,379 20,449,039 46,949,736Reduction of cost of fuel after optimizing routes and 14,763 23,199 18,915 31,973air traffi c control (million US$)CO2 emission reduction potential (T) 1,056,830 1,507,905 996,891 2,288,800Total CO2 emission reduction (T) 144,113 205,623 135,940 312,109Total cost of fuel saving (million US$) 2,013 3,163 2,579 4,360

Note: Cost of total fuel saved (million USD) 12,116Total CERs generated (T) 797,785@’ price of 13$/T US$ generated 1,844,479,345@’ price of 13$/T Million US$ generated 1,844

Th e CER price of 13$/T is taken as of the January 2009 price.Source: Analysed by the authors from the example of the Brisbane Green Project 2007.

Table 18.15 ATM System for Fuel Effi ciency and Emission Reduction (Per day)

Air Traffi c Management Average Fuel Average CO2 emissions Average Cost saved conserved (kg) reduced (T) (million USD)

100 per cent reduction in delays 25,000 1,219 1475 per cent reduction in delays 18,797 916 1050 per cent reduction in delays 12,500 609 7

Source: Analysed by the authors from study of Down to Earth (Refer to footnote 20).

Table 18.14 Delays on the Delhi–Mumbai Route for a Typical Working Day for the Financial Year 2008–9

Total average fl ights/day 80Considering delays in peak hours, avg. fl ights delayed 40in a dayAs per Down to Earth, delay in peak hours (mins) 30Avg. fuel consumption in the route(kg)/fl ight 1,813Total fuel use in the route (kg)/day 145,000Average CO2 emissions per day (T) 7,069Fuel use in delay hours (kg) 625Total fuel use in delay (kg) 25,000Average delay CO2 emissions per day (T) 1,219% of delay emissions to total emissions 14.71

Source: Author’s own (as per author’s analysis).

50 per cent of the traffi c on this route is never on time; the international standard is about 12 per cent. Hence, in order to achieve international standards, the route needs to increase effi ciency by 75 per cent. Analysis presented in Table 18.15 shows that if ATM is more effi cient and delays reduced by 75 per cent, India can match international standards and save fuel to the tune of 18,797 kg per day, saving $ 10 million. About


as forecasted winds, aircraft type and performance, convective weather, and scheduling requirements. While fl ex tracks do not provide the same level of effi ciency to individual aircraft that can be achieved in a UPR system, a fl exible track system may be the most effi cient solution. For example, in the oceanic environment, UPRs can create problems in sequencing aircraft, forcing some to fl y at sub-optimal fl ight levels.

– Dynamic Airborne Re-route Procedures allow air-craft to adjust their present position to a new point in order to realize savings in fuel or time. Th is is coordinated by the airlines with the fl ight crew, and sent to air traffi c control as a request to change route from the aircraft.

• Implementing Advanced Navigation Capabilities, RNAV-RNP– Required Navigation Performance (RNP) of Aircraft

Navigation (RNAV) is a type of PBN system that allows an aircraft to fl y a specifi c path between two three-dimensionally defi ned points in space. A navigation specifi cation that includes a requirement for on-board navigation performance monitoring and alerting is referred to as an RNP specifi cation. One not having such a requirement is referred to as an RNAV specifi cation. (For more details on RNP refer to optimizing routes and air traffi c section above). Integration of RNP into the ATM system provides greater fl exibility to balance operational requirements with community expectations.

– Gate to Gate Management initiatives which take into account potential delays along the entire route (aircraft do not take off if congestion is expected at destination) to prevent unnecessary holding patterns; aircraft in holding patterns at lower altitudes can burn fi ve times as much fuel a at cruising heights.

– Improved arrival/departure routes and profi les (for example, secondary radars installed at Delhi, Mumbai, Ahmedabad, Nagpur enabled ATCs to provide direct routings, improved route structure for improved air capacity due to direct routings which makes the aircraft spend less time in the air, burn less fuel, and emit less CO2).

• Optimizing Airport Operations through Collaborative Decision Making:– Collaborative Decision Making (CDM) is a joint

government/industry initiative aimed at improving

air traffi c management through increased informa-tion exchange among the various parties in the avia-tion community. Th e CDM programme is made up of representatives from the government, general aviation, airlines, private industry, and academia who are working together to create technological and procedural solutions to traffi c fl ow problems that face the National Airspace System (NAS).

– Improving airport infrastructure to support opti-mum capacity.

– Most airports need to have spare capacity, and it says that much of the existing capacity remains unused at the typical busy hour traffi c levels earlier.36 Signifi cant eff ort needs to be devoted to taking every last scrap of capacity out of the existing infrastructure, and develop much more infrastructure to handle the increasing traffi c in the future years.

• Economic regulations for the airports and air naviga-tion services.

• Creating a transparent and supportive regulatory re-gime on air traffi c management.

• Developing an equitable fi scal environment (for example, tax on fuel).

• Investing in appropriate airport infrastructure.• Building an effi cient airspace and air traffi c manage-

ment system.• Training the workforce that will drive the industry.

Summary and ConclusionsAviation is increasingly being singled out as a major source of GHG emissions, a signifi cant contributor to global climate change, and a source of air pollutants. From the study it was observed that aviation contributes to 2 per cent of global CO2 emissions and 13 per cent of transport emissions and 8 per cent of global NOx emissions. Aviation’s CO2 emissions rose by 4.5 per cent, from 675 to 705 million tonnes from 2000–4. For the same period fuel wastage increased about 13 per cent, reaching 18 per cent fuel use from the sector. Apart from the above mentioned fi ndings, the other major fi ndings from the research are as mentioned below:

• Aviation is a major contributor to the economic and social well-being of India; connects India to the world as a trading nation and fosters economic growth and prosperity.

• It provides access to remote communities where air transport may be the only realistic option.

36 ICAO (2009a).


• Th e aviation sector internationally is growing at 5 per cent per annum (PA)

• Aviation emits gases like CO2, CH4, NOx, N2O, soot, contrails and cirrus which have much more impact than the other sectors.

• Aviation’s share of GHGs has not grown since 1990 although aviation has grown substantially.

• Aviation energy consumption is 15 per cent of total transport sector.

• Th ere are many uncertainties in estimating emissions as the level of understanding of all the gases is not known. Gases like soot, contrails, and cirrus which have much more impact are not known.

• Th ere is a scientifi c concern that, despite the very low levels of GHG emissions from commercial aircraft op-erations, the standard cruise altitudes of those aircraft could compound the eff ects of their GHG profi le through a process that is commonly referred to as radiative forcing. Notably, there is signifi cant uncer-tainty within the scientifi c community as to the extent and relevance of this process on the overall GHG foot-print of the industry. Th e most recent IPCC report of 2007 concluded that contrails contribute a small radia-tive forcing impact with a low level of scientifi c under-standing. It is essential that more scientifi c resources be devoted to this particular factor in the overall debate in order to better understand and respond to this issue.

• According to predictions of IPCC, CO2 is to be increased by 258 per cent (1991–2015) and NOx would increase by 411 per cent for the same period. It is also predicted that CO2 would and NOx would increase by 588 per cent and 411 per cent (1992–2050) respectively.

• Th e IEA forecasts that GHGs from the sector would increase by 90% by 2030 without any policy implica-tions taken.

• It was also found that there are various concerns and developments in mitigation of aviation emissions globally and in India. Th e following points are the crucial concerns in aviation emissions. Th ese concerns are important to be considered for improving the civil aviation sector and the emission reduction potential from the sector in India.

• Th e history of emission reduction strategies for started way back in 1969 although a proper framework to re-duce emissions started only in 1997 after the inclusion of domestic aviation in the Kyoto Protocol.

• Framework for mitigation of emissions although in-cluded in the Kyoto Protocol, the sector is working

only under ICAO to meet the targets.• Th ere is no proper legal framework for emission reduc-

tion for the sector.• NATCOM is the only framework to reduce emissions

from other sectors other than aviation in India.• Several steps by various governments and airlines have

been taken since Kyoto, but there is no international framework for the emission reduction.

• USA and UK have been the leaders in emission reduc-tion from aviation.

• Th ere are no policy frameworks for the emission reduc-tion internationally or in India.

• Despite its insignifi cance Indian aviation has grown in leaps and bounds with more than 12 per cent annual growth in the fl eet.

• Th e air traffi c is growing at an average of 5 per cent annually with around 8 per cent growth in 2008

• India ranks third in the world for addition of new fl ights increasing domestic passengers.

• Severe delays with 50 per cent of the traffi c getting delays at the major airports due to lack of infra-structure, mechanisms, and management systems to reduce delays, traffi c control or slot management for the sector.

• Th ere is no placed methodology or framework for the emission reductions in India.

It was also observed that there is signifi cant potential in emission reduction, fuel saving, and further cost saving in implementing various proposed operational strategies. Operational improvement-based three strategies proposed for India, have been suggested after studying various operations strategies and these operational strategies have been selected for their applicability to Indian conditions. Th ese could signifi cantly reduce emissions and improve the overall effi ciency on the Delhi–Mumbai route:

• ATM to reduce delays: Th e eff ective ATM can save fuel worth 10 million $ and further international standard of 12 per cent can be achieved by this mechanism.

• Continuous descent approach can save about 605,216 CERs and fuel worth 8 million $.

• Optimizing route can also save about 797,785 CERs and fuel worth 1844 million $.

Operational procedures can improve the overall fuel effi ciency of the sector and reduce the emissions. Th us by improving the routes approaches and departures, there could have been fuel savings up to 12,116 million $ dur-ing the study period for the study route.


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