Restricting use of reverse thrust as an emissions reduction strategy.

As more metropolitan areas approach "nonattainment" status for ozone, air pollution at airports is becoming an increasingly important topic. Most proposed emissions reduction strategies target passenger automobiles and airport ground service equipment (GSE). At many airports, the future growth in oxides of nitrogen (NOx) emissions from aircraft is likely to offset any reduction achieved from GSE or passenger vehicles. In some metropolitan areas, airports may be responsible for as much as 10% of the regional NOx. As a result, other alternatives are needed for emissions reduction at airports. Reverse thrust is commonly used along with wheel brakes to slow aircraft during landing and to "power back" aircraft away from a boarding gate. Currently, air pollution emissions generated during reverse thrust are not included in airport emissions inventories. Because the majority of aircraft NOx emissions occur off-airport during climb out and approach, reverse thrust can be responsible for an additional 15% or more of the on-airport NOx. Because this additional NOx is emitted over a relatively small area, it can create significant air quality impacts in the vicinity of the busiest airports. An attempt is made to quantify the air quality effect of NOx emissions produced during reverse thrust, using Dallas-Fort Worth International Airport as a case study. The significance of the airport's emissions from a regional standpoint and state implementation plan photochemical grid modelling are addressed.