It is expected that as traffic volumes increase transport services will be provided by larger capacity vehicles. In other words, vehicle capacity is expected to be positively correlated with demand. This does not seem to hold true in the operation of air transport services. The leading aircraft manufacturers predict that demand for air transport services will continue to rise in the next 20 years but they also predict that the average size of the worlds aircraft fleet will not change much. This situation is very much one of the main outcomes of open skies policies, the importance of service frequency in the competition between airlines. To keep load factors high while offering high frequency service airlines tend to reduce the size of the aircraft used. On short haul routes this phenomenon is even more apparent and especially on routes between hub airports, even though these routes and airports are often congested. This choice of service frequency and aircraft size has important environmental consequences which the paper aims to explore, evaluate and quantify. Assuming a typical short haul route, the environmental impact of a large (wide-body) aircraft and small (narrow-body) aircraft is compared in terms of noise pollution, local air pollution and climate change impact. The comparison between the aircraft is at three levels: emission, impact and cost of damage. Special attention is given to describe the methodology used to empirically evaluate transport operation impact on the environment, describing state of the art and the limitations still exist in such an empirical evaluation. Also, special attention is given to applying the methodology to air transport operation (mainly accounting for the flight profile e.g. the landing take-off (LTO) cycle and cruise altitude). Initial results show that operation of narrow-body aircraft (Airbus A320-200) results in a lower environmental impact than the operation of wide-body aircraft (Boeing 747-400) in terms of noise pollution, local air pollution and climate change, when measured in seat units. The aircraft models chosen for the analysis entered service about the same time thus represent similar level of technological development. The differences between the aircraft are sensitive to the seat capacity assumed but the conclusion is not. The environmental advantages of using smaller aircraft come mainly from reduction in NOx emission (which contributes to lower local air pollution and climate change impacts) followed by reduction in CO2 emission. The results suggest that competition between airlines, which leads them to meet new demand mainly through higher frequency and smaller aircraft, rather than lower or similar frequency and larger aircraft, has environmental advantages. Yet, against this, further analysis is required to consider the environmental burden of congestion which is associated with the choice of high frequency and small aircraft as well as the environmental burden of building additional runways, which is another consequence of the choice of relatively small aircraft and high frequency. These issues are discussed in the paper as well as the environmental tax implications for runway slots and landing charges. For the covering abstract see ITRD E137145.
Abstract