A380 Effect on Capacity

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The Effect of the Airbus A380 on Runway PassengerThroughput

Alexander Donaldson

December 8th 2009

1 Background

The Airbus A380 can carry the most passengers and is also the heaviest commercial pas-senger aircraft to have entered service. The entry into service of the aircraft requiredcareful management by the airports, airlines and aviation authorities that would handlethe aircraft in order to minimize the disruption caused to the air transportation system.Airports were required to upgrade runways, taxiways and gates to deal with both the sizeand passenger volume of the A380. The authorities responsible for aviation safety wereparticularly concerned about the danger posed by the wake of such a high gross weight air-craft and initially took a conservative approach to wake separation standards which couldpotentially have reduced the passenger capacity at airports served by the A380. This studywill examine the tradeoff between the additional passenger capacity of the A380 and theadditional wake separation that the aircraft requires.

1.1 The Aircraft

The A380 entered into service in October 2006 with Singapore Airlines after an 18 monthdelay due to a variety of technical issues during development of the aircraft. At the timeof writing (November 2009) only 20 A380s have entered service [1], with a production rateof approximately 1 aircraft a month for 2008 and 2009 [2] potentially increasing to 20deliveries in 2010 [3]. This means that the impact of the A380 on the air transportationsystem to date has been gradual and sparsely distributed. However as more of these aircraftenter service in the coming years the effect of their operations will become more significantat the major international hubs where they operate.

For the purposes of this study the seating capacity of the A380 is an important variable.However there is considerable variability in this value even amongst the 20 aircraft delivered

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Figure 1: Current (November 2009) A380 Orders and Deliveries by Airline [1]

to date from a minimum of 450 seats in the aircraft operated by Qantas up to 525 seatsin the aircraft recently delivered to Air France. This variation in seating capacity makesa significant difference in the runway passenger throughput, therefore the capacity modelwill be run at these high and low bounds.

1.2 Integration into the Air Transportation System

In addition to an unprecedented passenger capacity for a commercial airliner, the size andweight of the A380 brought with it the likelihood of an exceptionally powerful wake. Duringdevelopment of the aircraft and the flight test program the International Civil AviationOrganization (ICAO) recommended a very conservative separation criteria of 10 n.m. for

all aircraft following the A380 (Table 1a) on approach, unless that aircraft was anotherA380 in which case there was no wake separation requirement (the A380 could follow anyaircraft including another A380 without any wake separation requirement). Just before the

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entry into service of the A380 the ICAO draft guidance was revised based on the results ofan extensive wake vortex measurement campaign carried out by Airbus. The final ICAOguidance was to simply add two nautical miles to the separation required behind a Heavyaircraft (Table 1b. This change in guidance had important implications for the throughput

achieved by the A380 as will be demonstrated in this paper. The United Kingdom CAAlargely mirrors the ICAO guidance with modifications to fit its own weight categorizationscheme (Table 1c). It is interesting to note that the UK CAA found it necessary torevise upwards the ICAO separation guidelines with regard to the A380 as a followingaircraft, based upon operational experience with the aircraft in busy UK terminal airspaceenvironments [4]. The United States FAA is taking a more conservative approach toA380 operation requiring separations (Table 1d) greater than the ICAO recommendationparticularly with regard to Medium and Light aircraft Following the A380.

Table 1: Different Approach Separation Standards (R denotes Radar separation minimumapplies - 2.5 n.m. for JFK and LHR)

(a) Initial ICAO Guidance

FollowingA380 H M S

Leading A380 R 10 10 10

H R 4 5 6M R R R 5L R R R R

(b) Nov. 2009 ICAO Guidance

FollowingA380 H M S

Leading A380 R 6 7 8

H R 4 5 6M R R R 5L R R R R

(c) United Kingdom CAA

FollowingA380 H UM LM S L

Leading

A380 4 6 7 7 7 8H 4 4 5 5 6 7

UM R R 3 4 4 6LM R R R R 3 5

S R R R R 3 4L R R R R R R

(d) United States FAA

FollowingA380 H B757 M L

Leading

A380 6 6 8 8 10H R 4 5 5 6

B757 R 4 4 4 5M R R R R 4L R R R R R

1.3 Example Airports

The impact of the A380 on three major airports will be examined in this paper. These

airports have been chosen because they have different modes of operation and mixes ofaircraft sizes, yet they are all expected to receive a significant number of A380 operationsin the coming years.

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(based at DXB) large order for 58 of the type (Figure 1). The airport also adds a thirddistinct separation standard by applying the ICAO recommendations without modification.Like JFK, Dubai International has a pair of parallel runways assumed to be operatingindependently with mixed arrivals and departures for the purposes of this study.

Figure 4: Dubai International Airport Layout

2 Methodology

This study compares the passenger throughput and arrival capacity of the three studyairports for the three cases of moving heavy operations to a 525 seat A380, a 450 seat A380and a 418 seat 747-400. The A380 cases include the appropriate higher wake separationcriteria required by that type of aircraft, while the 747-400 case reflects a simple up-gauging of the heavy category aircraft with no additional separation required.

The second part of the study looks only at LHR and compares the effect of applying thefour different described in Table 1 to the LHR operations to examine the behavior of thesecriteria for a common set of operations.

2.1 Runway Capacity Model

Simple queueing theory will be used to model runway capacity of the airports being studied,using the model described in de Neufville and Odoni [8]. The time separation (in seconds)

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between a lead aircraft in weight category i and a following aircraft in category j can befound from Equation 1.

Tij = max3600r + sijvj

r

vi , od2 + max(oi, od1) for vi > vj

(1)

Tij = max

3600

sij

vj

, od2 + max(oi, od1)

for vi vj

The time required per arriving passenger (in seconds) can then be calculated for differentsequences of arriving aircraft as shown in Equation 2.

Tpax,ij =Tij

ci(2)

Given Tij and Tpax,ij it is possible to calculate the airport arrival capacity using the matrix

of likelihoods of any given pair of arrivals (pij).

Cops =3600(nr)K

i=1

Kj=1(pij Tij)

(3)

Cpax =3600(nr)K

i=1

Kj=1(pij Tpax,ij)

(4)

2.2 Model Inputs

The required inputs for the runway capacity model were collected from a wide variety of

data sources with reasonable assumptions being made where data was unavailable. Themodel inputs are summarized in Table 2 and where appropriate are further explained inthis section.

2.2.1 Final Approach Path Length

The final approach path length (r) is the distance over which air traffic control can nolonger separate aircraft based on speed since the aircraft are preparing to land. At LondonHeathrow this distance is a minimum of 4 n.m.[9] and at JFK it is 5n.m[10]. The approachpath length for Dubai International could not be found and was therefore assumed to bethe same as used at JFK so as not to introduce an unnecessary additional variable.

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Table 2: Summary of Inputs to the runway capacity model

LHR JFK DBX

Approach

Length (r) 4 n.m. UK CAA[9] 5 n.m. FAA[10] 5 n.m. AssumedBuffer time (bi) 10 seconds (Assumed) [8]

Number ofRunways(nr)

1 segregated 2 mixed independent

Separation (sij)UK CAA (Table

1c)US FAA (Table 1d) ICAO (Table 1b)

ApproachVelocity (vi)

Based only on Boeing aircraft in schedule

Aircraft Mix(pij)

2008 FlightTimetable (4 week

sample)

2008 ETMSDatabase (4 week

sample)

2004 AnnualOperations

ArrivalOccupancy Time

(oa)Based on data from LHR Study

Departure set-uptime for (od1)

Not Needed 45 s (Assumed) [8]

Departures rolltime (od2)

Not Needed 60 s (Assumed) [8]

PassengerCapacity (ci)

Aircraft manufacturer data for typical multi-class configuration

2.2.2 Approach Velocity

Aircraft approach velocities vary significantly depending on the weight of the individualarriving aircraft, because of this it is a difficult process to estimate actual approach ve-locities. Boeing provides a document [11] with reference approach speeds which was usedto estimate speeds for this study. The Boeing speeds were applied to all Boeing aircraft(by sub-type e.g. 737-800) in the operational data sets and then averaged over the weightcategories in use at each of the study airports. Aircraft that were not manufactured byBoeing or McDonald Douglas were not included in the approach speed calculation. Thismethod provides a reasonable estimate for the approach speeds given the large number ofBoeing aircraft represented at the study airports and the wide range of weights of theseaircraft.

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2.2.3 Aircraft Mix

The probability (pi)of any given arrival being from a certain weight category is assumedto be equal to the proportion of all arrivals that are from that weight category. For

LHR and JFK the proportion of aircraft from each weight category was estimated throughexamination of 4 weeks of arrivals information from 2008. The first week in February,May, August and November were chosen to provide a mix of different travel seasons whileavoiding the holiday period. For DXB only aggregate data from 2004 was available. Giventhe already high proportion of heavy jets in this data no additional scaling was performedto adjust the mix of aircraft to 2008 levels. Once the probability vectors were compiled theprobability of observing a pair of arrivals i followed by j is simply obtained by multiplyingtogether the two probabilities pi and pj .

The measured values of pi are shown in Figure 5. It is important to note the proportion ofheavy aircraft at each airport, with DXB having significantly more heavy arrivals than JFKand LHR. A380 operations were simulated by moving a percentage of the heavy operationsat each airport to A380 operations. The model was run for up to half of the heavy operationat each airport being converted to A380s.

(a) At LHR (b) At JFK (c) At DXB

Figure 5: Distribution of aircraft weight categories at each study airport

2.2.4 Arrival Runway Occupancy Time

A study conducted in 2005 at LHR [12] measured the runway occupancy times for 170arrivals at London Heathrow for a wide range of different aircraft types and was conductedduring good visibility for a dry runway. The results of this study were averaged acrossthe weight categories appropriate for LHR, JFK and DXB. Given that runway occupancy

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time measurements for JFK and DXB were not readily available this data provides real-istic estimate of those times and was therefore used across all the airports in this study.The actual runway occupancy time may vary based on actual taxiway geometry and howexpeditiously pilots vacate the runway.

2.2.5 Departure Runway Occupancy Time

Data could not be found for the runway occupancy time of departing aircraft, thereforethe estimates given in de Neufville and Odoni [8] were used. These

3 Results

3.1 Impact at Different Airports

The runway capacity model was run using the inputs described in Section 2.2, for bothlow (450 seats) and typical (525 seats) aircraft passenger capacities as well as a baseline747-400 with 418 seats. The results of this analysis are compared in Figure 6 and in detailfor each airport in Figure 7. The results show that runway passenger throughput doesincrease in all cases however in the lower capacity A380 case the gains are marginal. Anygains in passenger capacity come at a cost in terms of operations per hour.

The comparison with the 747-400 shows that in all cases a move to 747-400s (which haveno addition separation requirements) would increase the passenger throughput more thanany of the A380 configurations modeled. This implies that if passenger throughput werethe only motivation for customers of the A380 then a high capacity Heavy aircraft would

better suit their needs. Fortunately for Airbus the A380 has other economic, environmentaland passenger comfort benefits over other Heavy aircraft.currently on the market

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Figure 6: Comparison of the effect of the A380 on operations at LHR, JFK and DXB for450 seat and 525 seat variants of the A380 and a 416 seat 747-400

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(a) At LHR (b) At JFK

(c) At DXB

Figure 7: Impact of A380 Operations on Arrival Capacity in terms of operations (black)and passengers (colored - light: 450 seat A380, dark: 525 seat A380)

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3.2 Effect of Different Separation Criteria

The comparison of the effect of different separation criteria Figure 8 shows considerablevariability in the effect of the different criteria on a common set of operational data. It

is particularly clear why the ICAO interim guidance was revised just before the A380entered service - the interim guidance would have caused a substantial loss in passengerthroughput (difference between red and gray line in Figure 8). Also of note is the factthat the conservative FAA guidance leads to a reduction in throughput for the low densityA380 configuration when applied to Heathrow. These results highlight the importance forregulatory agencies for finding the right balance between ensuring safety and improvingthe efficiency of the air transportation system.

Figure 8: Comparison of the effect on operations at LHR of different separation criteria

(UK CAA, US FAA, ICAO initial and ICAO final guidance)

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4 Conclusions

This study has shown that the A380 does not have a detrimental impact on passenger

throughput as some members of the aviation industry had fear it would. The increasingnumbers of A380 operations at hub airports around the world will however have a signifi-cant impact on the breakdown of their traffic by weight category. Major international hubswill operate most efficiently if the traffic mix is heavily weighted towards Heavy and A380category aircraft. For airports (such as JFK) that expect to continue operating a substan-tial number of lighter aircraft as well as several A380 operations careful management ofthe A380 operation will be required to ensure that the new aircraft has a positive impacton their airport.

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References

[1] Airbus. Orders and deliveries spreadsheet. http://www.airbus.com/fileadmin/

backstage/documents/od/November1_2009.xls , November 2009.[2] Max Kingsley-Jones. Dubai 09: Airbus set to decide on A380 production re-

vamp. http://www.flightglobal.com/articles/2009/11/17/335080/dubai-09-airbus-set-to-decide-on-a380-production-revamp.html, November 2009.

[3] Max Kingsley-Jones. Airbus slows A380 final assembly ramp-up. http://www.flightglobal.com/articles/2009/05/14/326416/airbus-slows-a380-

final-assembly-ramp-up.html, May 2009.

[4] David Kaminski-Morrow. http://www.flightglobal.com/articles/2009/01/26/321601/uk-rethinks-a380-wake-separation-from-heavy-jets.html, January2009.

[5] Civil Aviation Authority. London heathrow aerodrome chart. http://www.nats-uk.ead-it.com/aip/current/ad/EGLL/EG_AD_2_EGLL_2-1_en.pdf , August 2009.

[6] BAA. BAA heathrow website: Mixed mode. http://www.heathrowairport.com/portal/page/Heathrow%5EGeneral%5EOur+business+and+community%

5EFuture+growth%5EMixed+mode/1c8851dcd7423110VgnVCM10000036821c0a___

_/448c6a4c7f1b0010VgnVCM200000357e120a____/ .

[7] FAA. New York JFK airport diagram. http://www.naco.faa.gov/d-tpp/0913/00610AD.PDF, December 2009.

[8] R. De Neufville and A.R. Odoni. Airport systems: Planning, design, and management.McGraw-Hill Professional, 2002.

[9] Safety Regulation Group. CAP 493 Manual of Air Traffic Services Part 1. CivilAviation Authority, November 2009.

[10] Federal Aviation Administration. Order JO 7110.65S Air Traffic Control, change 1edition, February 2008.

[11] Boeing. Airport reference code and approach speeds for boeing airplanes. http://www.boeing.com/commercial/airports/faqs/arcandapproachspeeds.pdf , Au-gust 2007.

[12] British Airways and BAA Heathrow. Results from two surveys of the use of reversethrust of aircraft landing at heathrow airport. http://www.dft.gov.uk/adobepdf/

165217/282786/6_ENV1128.pdf, November 2005.

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A380 Effect on Capacity