Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
Phase of Flight Fuel NO x CO HC
Above 3000 m 9,683 204.3 197.1 56.7
Below 3000 m 219 4.0 1.1 0.1
Surface 358 1.2 13.2 3.1
Total 10,259 209.5 211.4 59.9
% Savings 6.1 9.9 12.7 18.0
*Annual savings in millions of pounds
8.2.5. Environmental Benefits Associated with CNS/ATM Implementation
8.2.5.1. Potential Environmental Benefits
Several studies associated with implementation of CNS/ATM systems have been carried out. Although some of these studies state their results in terms of cost/benefit
and associated fuel savings and do not specifically address the environment, obvious correlations to reduced gaseous emissions (including NO x and carbon dioxide)
can be drawn. Table 8-1 provides a summary of results from several case studies; this summary is taken from a paper presented by ICAO during the worldwide CNS/
ATM systems implementation conference held in Rio de Janeiro in May 1998 (ICAO, 1998b). A preliminary EUROCONTROL study considered various ATM strategies
and concepts that have the potential to reduce fuel burn. For two particular scenarios-free route airspace above 10,200 m and unconstrained "direct flight gate-to-gate"potential
savings of 1-2 and 7-8% were estimated, respectively (EUROCONTROL, 1997b). Table 8-2 presents the results of a preliminary assessment of potential fuel
savings and resulting environmental benefits resulting from introduction of CNS/ATM in the national airspace system of the United States for the year 2015 (FAA,
1998b).
8.2.5.2. Rebound Effects
Introduction of capacity- and efficiency-enhancing measures such as those associated with CNS/ATM systems may attract additional air traffic. This phenomenon is
referred to as the rebound effect. Introducing efficiencies hitherto not available to operators-efficiencies that result in lower fuel consumption and subsequently lower
operating costs-may reduce fares and stimulate traffic and growth beyond that already anticipated based on the forecast demand for air travel. This eventuality cannot
be overlooked because the net effect could be an increase in air traffic and consequently an increase in fuel burn and emissions. It is unclear to what extent any
additional emissions caused by a rebound effect might offset anticipated reductions in emissions arising from CNS/ATM systems implementation. No studies providing
evidence on the existence or size of the rebound effect have been carried out.
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