In the UK there is a scheme whereby troublemakers who are banned from one pub in an area are banned from them all - a simple message conveys the information to the other pubs. In these days of electronic communications would it not be possible for the airline which has uncovered the fake pilot to send a simple, general email to all other airlines stating simply that Fred Bloggs, Evan Evans or whoever had been sacked because of irregularities in his paperwork? It could also be accompanied by a recent photo - say a copy of his security pass photo. I know it sounds a bit simplistic, but sometimes the simple things work well.