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6 I.3Application of the Current To project the certification values to other temperatures and Emission Model to Idle pressures, the EDMS uses the Boeing Fuel Flow Method 2 Phase Emissions (BFFM2) (DuBois and Paynter 2006). The premier method for calculating the engine emissions uses established semi The Emissions and Dispersion Modeling System (EDMS) empirical relationships between emissions and combustion was developed by the Federal Aviation Administration (FAA) pressure and temperature and is known as the P3T3 method. and the US Air Force to assess air quality impacts of proposed The P3T3 calculations (NEPAIR 2003, Sarli et al. 1975) are airport development projects (FAA 2006). It has become the based on several parameters that are engine specific and not preferred computer model for air quality analysis at airports (Anderson et al. 2007). The principal source of emissions widely available or published. The BFFM2 approach is sig- data for the aircraft engines is the ICAO emission databank nificantly more general and estimates emissions performance (ICAO 2006). The protocol for emissions performance testing using only the engine databank values. The comparisons of for carbon monoxide, nitrogen oxides (NOx), and unburned NOx emissions predictions based on BFFM2 with those hydrocarbons is described in ICAO Annex 16 (ICAO 1993) and based on the P3T3 method are excellent for a wide variety of SAE Aerospace Recommended Practice (SAE 2006). The ICAO engines operating at different ambient temperatures, pressures emissions databank tabulates exhaust emissions performance (altitude), and relative humidity. The comparisons of CO and and other engine characteristics at four named conditions that UHC emissions are reasonable, but there are discrepancies. It is are nominally indicative of operational states at the airport: particularly challenging for the BFFM2 to use the logarithmic takeoff, climb-out, approach, and idle. Each of the tabulated extrapolation of the emissions data at 7% thrust and 30% thrust emissions values has either been measured at or scaled to the to project emissions at the lower thrust values typical of actual reference pressure (1 atm) and temperature (15C). operational use (DuBois and Paynter 2006).