On September 8, 2008, the FAA announced its intention to begin requiring that the sponsors of nonprimary hub airports include a list of based aircraft when submitting a grant application under the Airport Improvement Program (AIP). The FAA considers this information relevant to its consideration of proposed AIP projects at these airports. Many airports historically have had difficulty identifying based aircraft, defined in the FAA notice as registered, operational aircraft at an airport for the majority of the year. The FAA is accepting comments through October 8, 2008.