## Aircraft 

Aircraft emissions for a criteria pollutant emissions inventory are computed in EDMS/AEDT by factoring total aircraft operational activity against a database of aircraft/engine-specific emission factors based on engine manufacturer, model, and aircraft operational mode within the cycle. For the purposes of emissions inventory, an LTO cycle consists of operational modes: 

• Approach : The airborne segment of an aircraft’s arrival extending from the start of the flight profile (or the mixing height) to touchdown on the runway; 

• Taxi In : The landing ground roll segment (from touchdown to the runway exit) of an arriving aircraft, including reverse thrust, and the taxiing from the runway exit to a gate; 

• Startup : Aircraft main engine startup (for VOC only) occurs at the gate and is considered in EDMS/AEDT for ICAO certified engines only; 

• Taxi Out : The taxiing from the gate to a runway end; 

• Takeoff : The portion from the start of the ground roll on the runway, through wheels off, and the airborne portion of the ascent up to cutback during which the aircraft operates at maximum thrust; and 

• Climb Out : The portion from engine cutback to the end of the flight profile or the mixing height. 

EDMS/AEDT calculation of emissions within the LTO relies on two main categories of input: (i) aircraft fleet and operations, and (ii) time within each mode of the LTO cycle. 

## Aircraft Fleet and Operations 

At a minimum, EDMS/AEDT requires definition of an aircraft fleet (i.e., the types of aircraft using the airport and their assigned engines) and a level of operations (i.e., arrivals/departures/touch-and-go’s, or LTO) assigned to each member the a ircraft fleet. EDMS/AEDT can accept varying levels of detail depending on the extent to which aircraft operational parameters at a given airport are available or known. These range from the selection of a generic aircraft fleet with “default” engines selected by EDMS/AEDT, to the identification of specific airframes and engines based on an air carrier’s market information, to the modeling of individual flights based on a flight schedules or radar data. Typical sources of data that can be used to identify and define these parameters can be found within Appendix F ( Data and Information Sources ). 

## Times in Mode 

EDMS/AEDT functionality currently calculates a performance- based time in mode for the takeoff, approach and climb out (i.e., the aloft) components of the LTO cycle, which is based upon aircraft flight profiles, characteristics of individual aircraft, and meteorological conditions. Users are allowed to modify some of this information, such as aircraft takeoff and weights or the local meteorology, allowing for a more site-specific characterization of emissions aloft. Further, EDMS/AEDT currently only consider takeoff, climb out and approach emissions up to the atmospheric “mixing height” for the area, defined as the vertical extent in atmosphere over which pollutants no longer mix downward to ground level. 

