Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
*Information provided by Japan Airlines.
Apart from load factor, aircraft type, and level of technology, the configuration of an aircraft (number of seats, distribution between seating and cargo capacity) also has
an important influence on fuel burned per passenger-km. The configuration is determined by the airline in consultation with the aircraft manufacturer and can be altered
during the aircraft's lifetime. It differs between airlines and is based on market considerations. An example is provided by the way Japan Airlines configures its Boeing
747-400 aircraft. The 747-400 in long-range full passenger configuration has 262 seats, whereas the 747-400D used in high-density local Asian service has 568 seats,
even when used in similar lengths of flights (see Table 8-4). Seat configuration can also vary in smaller aircraft. For example, Tarom Romanian Air Transport operates
BAC 1-11 aircraft in configurations with 104 economy passengers or a combination of 12 business and 77 economy passengers. Tarom also operates Boeing 737-
300s with the same operating weights with 12 business and 120 economy passengers or 20 business and 102 economy passengers.
Most calculations of the mobility efficiency of passenger aircraft do not take into account the cargo that is carried in aircraft used for scheduled passenger services. For
example, in 1995 about 28% of tonne-km flown by British Airways operations consisted of freight (British Airways, 1998a), much of which was carried on passenger
aircraft. The United States reported 33.9% for all types of passenger aircraft in 1996 (Bureau of Transportation Statistics, 1997). The 1996 U.S. cargo load factor for
freight carriers was reported to be 61.8% for all aircraft types. Although relatively little freight is carried on short-haul passenger service, the carriage of freight might be
adding a significant penalty to the perceived mobility efficiency of passenger air transport for long-haul flights.
Optimization of aircraft configuration and load factors can result in reduced emissions. This conclusion is supported by data presented in Tables 8-3 and 8-4. Airline
economics dictate that costs, including fuel costs, be minimized, therefore that the load factor be optimized. As an illustration of the development of load factors for all
domestic and international scheduled services, International Air Transport Association (IATA) statistics show an average 0.4% per annum increase in load factor over
the past decade (IATA, 1996). These data are consistent with data in ICAO (1996), which showed an increase in load factor of 4% in a period of 10 years. However, it
is unclear whether the load factor can continue to grow indefinitely without consequences to passenger service. Moreover, load factor and aircraft configuration are
driven not only by the need for improved efficiency but also by market considerations.
The increase in demand for air travel is an important factor in aircraft capacity utilization. (Chapter 9 describes the main drivers for this increase.) A second important
factor is the (further) development of the "hub and spoke" system in some parts of the world, such as the United States and Europe. Because transport efficiency is not
always optimized by direct point-to-point travel, air travel has evolved from direct connections between major city pairs to a complex network that includes
consolidation hubs. Costs are minimized by maximal use of single-sector, out-and-back operations. By combining these sectors in a hub-and-spoke network, an
efficient multiplication of potential point-to-point markets served can be achieved. Use of the hub-and-spoke system results in greater distances than direct point-topoint
flights; it can also result in fewer aircraft operations for the entire system. Any area of the world with, for example, 500 airports will have about 250,000 potential
point-to-point flights. For many pairs of airports, however, a direct flight will never occur except where demand makes direct routes economically viable.
Recent studies (e.g., Peterse and Boering, 1997) have suggested that apart from further intensification of the hub-and-spoke system, more point-to-point connections
are likely to be introduced. This "hybrid" development arises for several reasons:
. Two-engine aircraft built for extended twin operations (ETOPS) over water are available.
. Further segmentation of the air transport market. Business passengers are prepared to pay more for a direct connection instead of flying via hubs.
. Capacity problems at main hubs are likely to lead to growth at smaller, secondary hubs.
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