Data Source  Description  Aviation System  Performance Metrics  (ASPM)  Provides detailed data on flights to and from the ASPM airports; and all flights  by the ASPM carriers, including flights by those carriers to international domestic non-ASPM airports. All IFR traffic and some Visual Flight (VFR) traffic are inclu ded. ASPM also includes airport weather, configuration, and arrival and departure rates. This combination provides a robust picture of air traffic activity for airports and air carriers. This  information is proprietary and requires an FAA re gistered user name a password. After acquiring a login from FAA, this information can be accessed  at the following website: https://aspm.faa.gov/aspm/entryASPM.asp?lite=y.  Bureau of Transportation  Statistics (BTS) On-Time  Statistics  Provides aircraft statistics, including taxi in and taxi -out data for airlines at 287 airports. Annual data available beginning with the year This  information  can  be  accessed  at  the  fol g  webs http://apps.bts.gov/xml/ontimesummarystatistics/src/dstat/OntimeSummaryDep  atures.xml.  operational models (i.e. SIMMOD) and  the databases shown in  Table A1-5  ( Taxi Time Input  Data Sources ).  Source: FAA; and BTS, 2013.  Notably, EDMS/AEDT estimates aircraft main engine PM emissions only for aircraft with ICAO  certified engines using the First Order Approximation FOA3/FOA3a methodology  (see  Section  A1.2 ,  EPA Methodology ).  EDMS/AEDT contains a database of aircraft engine emission factors for CO, NO$_{x}$, PM, SO$_{2}$, and  VOCs based on engine make and model for each of  the four engine operating modes ( i.e.,  taxi/idle, takeoff, climb out, approach). These  emission factors are based on  the ICAO  Engine Exhaust Emissions Databank 10 , manufacturer data, and for older aircraft, data  contained  in EPA’s AP-42, Volume II, Section 1. 11  EDMS/AEDT does not report Pb emissions directly, but many users calculate Pb emissions as a  post-processing step to running EDMS /AEDT. Thus, one should  use EDMS’s/AEDT’s fuel  consumption information (only for GA aircraft piston engines that use Avgas) coupled assumptions of how much Pb is in the fuel and how much Pb remains in the engine Equation A1-4 ,  Lead Emission Calculation ).  Generally, aircraft engine emission factors are expressed as grams of pollutant emitted kilogram of fuel burned or pounds of pollutant per 1000 pounds of fuel consumed. When these  are multiplied by the fuel flow rates in kilograms per second  or pounds per second, emission  rates in grams-per-second or pounds-per-second, respectively, are produced.  10 ICAO’s Aircraft Engine Exhaust Emissions Databank available at the following website:  http://easa.europa.eu/document-library/icao-aircraft-engine-emissions-databank.  11 EPA’s  AP-42, Volume II: Mobile Sources  is no longer maintained and has been superseded by more recent EPA  publications, refer to http://www.epa.gov/otaq/ap42.htm for additional information.  8$_{ }$ A1.3.4  Emission Factors  Table A1-5. Taxi Time Input Data Sources  APPENDIX A1$_{ }$