Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
Aircraft operate most efficiently at specific cruise altitude; generally, less fuel is consumed at higher altitudes, but more engine thrust and equipment may be required to
reach those altitudes. Any requirement to stay, for example, below the tropopause would undoubtedly increase fuel consumption. In that case, flights travelling close to
the North Pole during the winter would have to descend to levels that could be 2,500-5,000 m below the most fuel efficient level. Consequently, fuel consumption would
increase for many flights (ICAO, 1995). A study by Fransen and Peper (1993) showed that total fuel burned by aviation in the North Atlantic corridor would increase by
4-5% using flight level 310 (approximately 9,500 m) as the maximum allowed level; the increase for an individual flight could be as much as 20% (Lecht, 1994). This
restriction would lead to payload and range limitations because some current aircraft operate at or close to maximum range. Such limitations, in turn, could lead to
requirements for intermediate stops-resulting in less direct routes, increased flight times, and increased fuel burn. Another effect would be concentration of flights,
hence increased congestion, which would contribute to additional fuel burn.
Figure 8-4: CO 2 intensity of passenger transport (TEST, 1991; Whitelegg, 1993; Faiz et al., 1996; Centre for Energy Conservation and Environmental
Technology, 1997a; OECD, 1997a).
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