This link leads to FAA 3 letter designators
http://www.faa.gov/air_traffic/publications/atpubs/CNT/3-3.HTMOther examples ASQ = ExpressJet, QXE= Horizon Air, RPA Republic Airlines, CHQ = Chautauqua Airlines,
AZU = Azul Linhas Aereas Brasileira, POE = Porter Airlines, JZA = Jazz Air, PSC = Pascan Aviation
THT = Air Tahiti Nui
FLG is in as Northwest Airlink, they havent been about for a while. FLG = Pinnacle Airlines
LOF is in as Trans World Express again not been about for a while. LOF = Trans States Airlines
SPR is in as Eastern Flying Services but SPR = Provincial Airlines
FFT is in as Republic Airlines/Frontier but FFT = Frontier Airlines
PAL shows as Philippines, should read Philippine Airlines
While the aircraft may not display its flight ID three letter designator, the airline is usually available from the Navdata
Alan