
                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                NATIONAL VEHICLE AND FUEL EMISSIONS LABORATORY
                             2000 TRAVERWOOD DRIVE
                           ANN ARBOR, MI  48105-2498


									     OFFICE OF
									AIR AND RADIATION
May 23, 2023

MEMORANDUM

SUBJECT: Piston-engine Aircraft in Alaska

FROM: Marion Hoyer

TO:  EPA Docket # EPA-HQ-OAR-2022-0389


This memo documents a meeting held on October 27, 2022, between representatives of the Alaska Department of Environmental Conservation (AK DEC) and EPA to discuss the use of piston-engine aircraft in Alaska. The meeting attendees from AK DEC included Jason Olds, Barbara Trost, Nick Czarnecki, and Cindy Heil, and from EPA included Marion Hoyer.

The discussion focused on the importance of piston-engine aircraft in Alaska. 

In response to a request from the meeting attendees from AK DEC for information on EPA's National Emissions Inventory for 2017 emissions of lead from piston-engine aircraft in Alaska, both the state total, as well as airport-specific lead, EPA staff provided the file Docket ID EPA-HQ-OAR-2022-0389-0043 that has the landing and take-off data and lead emissions at all the airports in the U.S. EPA staff further explained that for many airports there are two entries; one for general aviation (GA) activity by piston aircraft and one for air taxi (AT) activity by piston aircraft. These are estimates based on the method posted on EPA's website at https://nepis.epa.gov/Exe/ZyPDF.cgi/P1009I13.PDF?Dockey=P1009I13.PDF. 

EPA staff further explained that to obtain the amount of lead at each airport during landing and takeoff, one needs to sum the GA and AT lead, and that to obtain the total amount of lead emitted in the state of Alaska from piston-engine aircraft, one would sum the amount of lead emitted at airports and the lead emitted in-flight, outside the landing and takeoff cycle.  EPA staff explained that EPA's estimates of lead emitted in-flight are calculated by allocating the lead emitted in-flight to states based on their share of total national landing and takeoff activity, as explained in the method at https://nepis.epa.gov/Exe/ZyPDF.cgi/P1009I13.PDF?Dockey=P1009I13.PDF.

EPA staff explained that this is because EPA's estimates initially start with a total amount of lead emitted by piston-engine using FAA estimates of the volume of leaded avgas consumed each year. Airport-specific lead is estimated based on the landing and takeoff activity (which is in the spreadsheet at Docket ID EPA-HQ-OAR-2022-0389-0043), but the in-flight lead must be included to be complete.

EPA staff further explained that, using these methods and the information provided, the total amount of in-flight lead estimated to be emitted in Alaska in 2017 is 4.0 tons and the total amount of lead estimated to be emitted in the landing and takeoff cycle is 3.6 tons.

Finally, EPA staff explained that with regard to the airport-specific lead inventories that EPA does not have fuel consumption estimates for the largest piston-engine aircraft used in Alaska (e.g., DC-6, C-46).  As such, the estimates of lead emitted at airports where these aircraft operate are likely to be underestimates.

