Although most U.S. airports use the same three-letter location identifier for the FAA and IATA, Wiscasset Airport is assigned IWI by the FAA and ISS by the IATA.
In contrast to most U.S. airports that use the same three-letter codes for both the Federal Aviation Administration (FAA) and the International Air Transport Association (IATA), Wiscasset Airport has distinct identifiers of IWI for the FAA and ISS for the IATA.