BACKGROUND

The takeoff phase contributes a large fraction of ground-level nitrogen oxides (NO_x) emissions from aircraft. Although takeoffs represent only a small proportion of the total flight landing-takeoff cycle, the emission rate is high because both the emission index (grams NO_x per kilogram of fuel) and fuel flow (kilograms per second) increase with thrust for most aircraft types, so that the NO_x emission rate is roughly proportional to the square of the thrust. This also means that the emission rate is very sensitive to the thrust used. Although NO_x emissions are particularly sensitive to thrust, fuel use (and therefore carbon dioxide, hydrocarbons, and particulate matter) are also thrust-dependent.

The current practice for modeling airport emissions assumes full (100 percent) takeoff thrust, yet operators often use reduced takeoff thrust settings, primarily to prolong engine life. The extent of this thrust reduction is limited by operational regulations, but may be as much as 25 percent for U.S. operators and greater for some foreign flag carriers. It is likely that the accuracy of emissions inventories could be improved by using takeoff thrust settings that better reflect actual operator practice.

Research is needed to develop a method for estimating aircraft takeoff thrust settings for a wide variety of commercial and general aviation aircraft, suitable for use in preparing airport emissions inventories.

OBJECTIVE

The objective of this research is to develop a guidebook, with an associated takeoff thrust-setting estimator tool, to help airports and their stakeholders more accurately reflect aircraft takeoff thrust settings used to calculate airport emissions inventories.

STATUS

Research complete.  The thrust-setting estimator tool, user guide, and contractor's report are published as ACRP CD-161.