Over the past five years, the Federal Aviation Administration has handed out nearly $18 billion in grants for almost 19,000 airport projects. In theory, these projects — funded through the FAA’s Airport Improvement Program — are supposed to enhance safety or protect the environment. In fact, according to a Subsidyscope analysis of FAA data (neatly assembled into a searchable database by Sunlight’s Kaitlin Lee), a fair amount of money has gone toward the building of parking lots and other questionable things.

We’ve only scratched the surface but have managed to extract a few interesting items from the database. Since the beginning of fiscal year 2005, for instance, airports in the Federated States of Micronesia, the Republic of the Marshall Islands and the Republic of Palau have received an impressive $173 million through the AIP. The sovereign Pacific island nations became eligible for AIP money in 2003 after signing a Compact of Free Association with the United States. Under the compact, the U.S. agreed to provide financial assistance in exchange for the granting of defense rights.

Another $82 million went to Guam International Airport. Back on the mainland, Plattsburgh International Airport in upstate New York secured $26 million. Fat sums went to a number of obscure, general aviation airports, to the annoyance of commercial aviation types who’d like more grant money to go to the hubs that accommodate the airlines. The AIP, they argue, is fed to a great extent by taxes on passenger tickets and jet fuel, yet a disproportionate share of the money goes to non-commercial airports.

Our database allows the public to find out what the FAA thought of projects at airports as big as O’Hare International in Chicago and as small as Beauregard Regional in DeRidder, La., before approving them. Through a Freedom of Information Act request, we obtained National Priority Ratings — NPRs — for every AIP project from Oct. 1, 2004 through Sept. 18, 2009. NPRs are assigned on a scale of 0 to 100, with 100 being the highest priority. NPRs for the Guam projects ranged from a lowly 19 (for utility improvements) to a respectable 66 (for an updated master plan). The Plattsburgh projects earned scores ranging from 17 (for a parking lot) to 93 (for a fire and rescue vehicle). And the projects in Micronesia, the Marshall Islands and Palau got scores ranging from 19 (to modify a service road) to 90 (for fire and rescue equipment). The FAA’s NPR threshold for discretionary grants (as opposed to formula-driven entitlement grants) is 41; for stimulus grants, 62. In both cases, projects scoring well below those numbers got in on the AIP bounty. In an August report, the Department of Transportation’s inspector general took exception to the way the FAA had dispensed some stimulus funds.

The database also can be searched by airport name and code, state and congressional district. Grants awarded under the stimulus act can be segregated from those awarded through the regular AIP process.