I once wrote up a list entitled "Defunct Airlines I Have Flown". I'm afraid it's sitting on the hard drive of one of the "Defunct Computers I Have Used", but I included totally defunct airlines like Braniff (the original), Eastern, Florida Express, Air Florida, Northeastern, Muse Air, etc. and in a separate category those that merged/were bought out in some fashion like Ozark, PeopleExpress, Alleghaney, Piedmont, Pan Am (the original), Frontier (the original, bought by PeopleExpress...), North Central, Southern, Air Cal, Northeast, National (the original), Western, etc. and coming soon TWA. I didn't try to include commuter carriers flying under someone else's logo (e.g. USAirways Express, etc.).