Description of the main sources of information

The main sources of information that are used in this chapter are airline operational statistics that typically contain information on the yearly average fuel intensity of different airlines and of the different aircraft in their fleets. The information on the specific fuel consumption is typically given as the fuel consumed per aircraft kilometre⁷ or per available seat kilometre (ASK)⁸ produced and per revenue passenger kilometre (RPK) transported or per available tonne kilometre (ATK) offered and per revenue tonne kilometre (RTK) transported or per revenue freight tonne kilometre transported (RFTK). The data material covers a broad range of scheduled airlines and charter carriers that are situated in Europe, in Asia and in the United States.

Most of the data for the European and Asian airlines are taken from their yearly environmental statements⁹ and from some overall operating statistics that are

7 The data for the number of aircraft kilometres flown are typically for the shortest great circle distance between the airports in question. That is, the aircraft actually often fly longer routings.

Therefore, there is a potential for reducing the specific fuel consumption per ASK and RPK by flying more direct routings.

8 The term available seat kilometre is a measure for transporting one seat one kilometre. The number of available seat kilometres produced by an aircraft is calculated by multiplying the number of seats available in that aircraft by the number of kilometres flown. Available seat kilometres is thereby a measure for the passenger capacity (i.e. the number of passenger kilometres that could be produced at the maximum passenger load factor) of a given flight.

9 Most notably, such yearly environmental statements are published by airlines such as British Airways, Lufthansa, Lufthansa Cargo, Lufthansa Condor, Lufthansa City Line, SAS, Swissair, Balair, Premiair, Air France, Finnair, Braathens, All Nippon Airways, Japan Airlines and Cathay Pacific Airways.

published by the Association of European Airlines (AEA)¹⁰ but much additional material have been requested directly from the airlines. Most notably, Lufthansa, All Nippon Airways and British Airways as well as the European charter carriers Premiair and Air 2000 have kindly assisted the author in getting access to detailed information on the specific fuel consumption of the aircraft in their fleets as well as the passenger load factors and the freight load factors and other operating statistics. Furthermore, some older studies of the fuel intensity of Lufthansa in 1989 and 1990 [Reichow 1990 and 1992] and of all the British Airlines in the 1980s [Martin and Shock 1989] are included to be able to compare today’s average operating statistics to those of earlier years.

Most of the data used for describing the fuel-intensity of the American air carriers have been requested from the United States Department of Transportation (DOT) that maintains a detailed statistical database describing the operating characteristics of American air carriers. For decades, the air carriers situated in the United States have reported their operating statistics to the DOT in the so-called “form 41” arrangement.

These data cover most aspects that are interesting for an analysis of the fuel consumption of the different aircraft and airlines. Most of the operating statistics for the American air carriers that are used here have been kindly provided in Excel spreadsheets¹¹ from the DOT. These data describe the average overall fuel intensity of a number of American air carriers in selected years from 1982 to 1999. Furthermore, quite detailed data have been provided on the airlines’ operating statistics in 1999. The 1999-data contains specific information on the fuel burn, the aircraft kilometres, the available seats, the average stage distances and the average passenger load factors by type of aircraft for all the aircraft types that are operated by the US air carriers.

Furthermore, some additional form 41 data that describe the fuel consumption of the aircraft that were operated by the Major¹² US air carriers in 1998 are taken from some

10 Most notably, some information from the Statistical Appendixes to Association of European Airlines’ (AEA) Yearbooks [AEA 1998, 1999, 2000c and 2001] are included. These statistics include operating statistics on the amount of cargo carried in the passenger aircraft that are operated by AEA member airlines.

11 These data are referred to in the text as [DOT 2001] describing the fuel cost and consumption and other operating statistics of the American Majors, Nationals and Regional airlines in selected years from 1982 to the present.

12 In 1999 there were 13 Major US scheduled airlines with annual revenues of over $1 billion.

Three of these, DHL, FedEx and United Parcel Service, are all-cargo carriers. The ten passenger carriers are Alaska, America West, American, Continental, Delta, Northwest, Southwest, Trans World, United and U.S. Airways. By January 2000 American Eagle and American Trans Air also became Majors [Air Transport Association 2000a].

recent articles published in the Journal “Aircraft Economics”. The data for 1998 describe the fuel intensity and the productivity of all-cargo aircraft [Aircraft Economics 1999d] and of narrow-body passenger aircraft [Aircraft Economics 1999c] and of wide-body passenger aircraft [Aircraft Economics 1999f]. These data are furthermore supplemented by some statistical sources from the American Air Transport Association (ATA)¹³ and by some overall statistics from the United States Department of Transport¹⁴ [DOT 1999 and 2000] and the United States Department of Energy¹⁵ [Davis 1995 and 1999]. Additionally, an older analysis of the “form 41” fuel consumption data that describes the impact of the 1973 and 1979 oil crisis’ on the operating economics of the Major American air carriers is included [Sarames 1984] as to be able to compare today’s fuel intensity by type of aircraft to that of the early 1970s.

It is likely, that there are some inconsistencies in the data material that describes the specific fuel consumption of different aircraft and airlines. For example, the airlines may use different methodologies for calculating the weight of the passengers and the freight that they are transporting. Furthermore, the information on the amount of freight that is carried in passenger aircraft is most often relatively scarce or non-existent in some of the statistical sources used here. It has therefore been necessary to use different types of estimates to be able to distribute the fuel consumption of passenger aircraft between the passengers and the belly-hold freight that they are transporting. There are also inconsistencies in the way the airlines attribute their fuel consumption to passenger and freight transport. Furthermore, there are differences in the way the airlines report their amount of revenue passengers transported. Some airlines may count all passengers whereas others exclude the passengers that are paying below a certain percentage of the normal fare. These inconsistencies are likely to be greater in cross-comparisons between the operating statistics of the European, the Asian and the American airlines

13 The operational statistics published in Air Transport Association’s yearbook [Air Transport Association 1999, 2000e and 2001] are used to derive information on the amount of freight that is carried in passenger aircraft.

14 Information on the overall yearly traffic performance (aircraft kilometres, average seats, available seat kilometres and revenue passenger kilometres) and the total fuel consumption, divided on domestic and international operations, of the American air carriers since 1973 are taken from the National Transportation Statistics that are published by the US Department of Transport [DOT 1999 and 2000].

15 Information on the overall yearly traffic performance (aircraft kilometres, average seats, available seat kilometres, revenue passenger kilometres and revenue freight tonne kilometres) and the total fuel consumption of the American air carriers since 1973 has been taken from the

than what is the case when only comparing the data for the American air carriers that are reported to the US Department of Transportation in the same format. The data for the US air carriers are therefore internally consistent. Because the operating statistics of the American air carriers cover a large number of aircraft and airlines these data are used for most of the analysis’ that makes cross-comparisons between a number of airlines. Some of the data inconsistencies are discussed further throughout this chapter.

The airline information is supplemented by various other sources, such as material from the aircraft producers and data from two modelling studies that gives information on the average fuel consumption according to the stage distance flown for a number of generic aircraft types [Gardner et. al. 1998] [Falk 1999]. Another modelling study that is mentioned briefly describes the increase in the specific fuel consumption per aircraft kilometre when the load factor increases [Daggett et. al. 1999]. These studies are drawn in because the data for the average yearly fuel consumption by type of aircraft does most often not offer insights to the fuel consumption connected to single trips of a specific length or with a specific load factor. Rather, the main part of the data reported by the airlines are average yearly data, that is, for example, averages for an airline or a number of airlines that are operating on a number of routes in a certain year.

Additionally, a rather large amount of new regional jets and turboprops are currently emerging at the market. Some data for their specific fuel consumption at short-haul trips are drawn in as to be able to assess their likely impact on the specific fuel intensity of short-haul passenger air travel in the future [Aircraft Economics 2000a, 2001a and 2001c]. Most of these regional aircraft have only recently been introduced into airline operation or are planned to be introduced within the next few years, and are therefore generally not yet included in the airline reporting for the recent years.

The section that describes the future prospects for improving the fuel efficiency of next-generation aircraft is based on estimates found in the literature as well as information from the aircraft producers [Vincendon and Wrede 1999] [Airbus 2000a] [ATR 2001].

The section on the long-term possibilities to improve the fuel efficiency of aircraft as well as the brief discussion of alternative fuels draws extensively on other sources such as the recent report from the Intergovernmental Panel on Climate Change “Aviation Transportation Energy Data Book that is published by the US Department of Energy [Davis 1995 and 1999].

and the Global Atmosphere” [IPCC 1999]. The brief mentioning of the possible contribution of aircraft engine emissions to climate change is also primarily drawing on the conclusions of this recent report.

Finally, the section that compares the fuel intensity of passenger air travel to that of other transportation modes draws on a number of studies of the fuel intensity of passenger cars [Færdselsstyrelsen 1999] [Schipper and Marie-Lilliu 1999] [EEA 2001]

and trains and buses [IPCC 1996b] [Roos et. al. 1997] [DSB 1998] [Jørgensen 1999].