Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
record indicates that aviation fuel productivity has increased considerably. ICAO estimates that, while aggregate
fuel consumption for the 1976-90 period grew approximately 60%, world civil air traffic (passengers, freight, and
mail combined) increased about 150%. These figures are explained by an increased average load factor, a more
optimal aircraft fleet mix, greater engine efficiency, and improved system capacity (Balashov and Smith, 1992). The
amount of fuel consumed and fuel productivity affect airline profits and ticket prices.
Of interest to the policymaker is the effect of a change in fuel price on airline cost and fare structures and on
passenger and cargo demand. Figure 10-1 shows the percentage of total annual airline expense attributable to fuel
cost for U.S. and world airlines over time and compares changes in this ratio against changes in the index of fuel
prices for the United States and the world. Data for the figure were extracted from industry and ICAO published
sources (ICAO, 1996b; Aerospace Industries Association of America, 1998). The data indicate that average fuel
cost across the industry has recently represented about 11-15% of operating costs, but has been higher during
times of high fuel prices (e.g., nearly 30% in the early 1980s). Further analyses of the impact of fuel prices on
demand and industry profitability are needed.
Against the background of these underlying trends, the potential role of mitigation measures is considered in further
reducing the growth of aircraft emissions by forcing technology, changing industry practices, and dampening growth
in traffic.
10.4.2. Regulatory Measures
Atmospheric environmental impacts associated with aviation emissions include greenhouse gas emissions, ozone
depletion, acidification, and impact on local air quality. Cruise altitude (above 900 m) aircraft emissions of interest
are CO 2 , NO x , particulates and aerosols, sulfur compounds, and H 2 O. Ground-level (altitude below 900 m) aircraft
emissions of interest to local air quality issues are NO x , carbon moNO x ide (CO), unburned hydrocarbons (HC), and
other volatile organic compounds. Ground-level CO 2 emissions from aircraft are of interest because of their effects
on climate. This section examines more fully two technology-based means for mitigating the adverse effects of
aviation emissions.
10.4.2.1. Operational Means to Reduce Emissions
Figure 10-1: Comparison of annual fuel
expense as percentage of total annual
operating expense for world and U.S.
airlines against world fuel and oil and
U.S. fuel cost indicies, 1970-96.
The environmental aim of air traffic system modernization and operational measures is to reduce fuel consumption, hence emissions, through improvement in the
overall efficiency of the air traffic system. For 1995, U.S. airlines reported a 79% "on-time" arrival rate for all domestic flights (i.e., flights arriving within 15 minutes of
schedule), including canceled flights and those with mechanical delays. For 1996, this figure was 75%. This decline indicates the scope of current congestion and
delay problems (U.S. Department of Transportation, 1998).
U.S. Federal Aviation Administration (FAA) data show that annual system delays of 15 minutes or longer (as a percent of total operations) have declined steadily from
2.2% in 1989 to 1.2% in 1997. Over that period, 55-70% of these delays were caused by weather; 25-35% were caused by terminal volume and closed runways and
taxiways (U.S. Federal Aviation Administration, 1977). FAA estimates of the total cost for air carrier delay (operating plus passenger time costs) grew from $6.5 billion
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