NEI documentation moving from FTP to?


I was looking at the methodology in the 2020 TSD for airport emissions (3.2.2) which highlights that the emission factors and further aviation documentation is available at the FTP site. These links are not available on the FTP site, so is there a place where these documents are stored?


“The emissions factors (EFs) used, as well as the
complete methodology for estimating aircraft exhaust from LTOs is in the aircraft documentation available in the document “2020 NEI Aviation Documentation” on the 2020 Supplemental data FTP site. For 2020 NEI, only
California and Georgia submitted aircraft emissions.”

The aviation supplemental documentation is available here:

The FTP site was down for some part of Friday – perhaps you tried to access it while it was down?

Or perhaps the link in the TSD is incorrect.

Thanks Alison, seemed like the website was down whenever I was checking for the file – it’s available now

Hi Alison, I still couldn’t find one piece of information that I assumed would be in these methodology documents. It seems like table 4-1 of the supplemental documents (for both 2020 and 2017 NEI, don’t include emissions factors for CO2, though the values are estimated. Is there a different location where those factors might be stated?

The CO2 factor is not listed in this documentation because it is computed by AEDT directly, like NOx. The listed factors are used to compute emissions for pollutants that are not directly computed. Here is some information that might be helpful:

From Section 5 of the AEDT technical manual(

Emissions of CO2 and H2O are modeled based on Jet Fuel A composition. Boeing conducted a review of the available fuel composition data and developed EI values that could be used to predict emissions solely based on fuel burn

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Thank you for clarifying!

An update to this:

Apparently for generic aircraft we have developed emission factors consistent with AEDT that we use for ‘Generic aircraft’

The factors are by SCC. Here are the generic CO2 factors:

Aircraft TypeCat Pollutant CAS No Emission factors (tons/LTO) Aircraft TypeCat2 SCC
MIL CO2 CO2 1.321E+00 NA 2275001000
AC CO2 CO2 2.418E+00 NA 2275020000
GA CO2 CO2 9.595E-02 prop 2275050011
GA CO2 CO2 4.966E-01 jet 2275050012
AT CO2 CO2 2.684E-01 prop 2275060011
AT CO2 CO2 6.858E-01 jet 2275060012