I've also tried some flight domains when I started off.. Didn't really work.
What airlines doesn't have great domains and do they really need a new name? Because it would be useless to have it as a redirecting site since no one would type-in "FlightEuro.com" to check flights..
And don't you think a big airline could afford a better domain than this one?
I have no end users in mind, that's your job. About auction you can try the main ones: GoDaddy, Sedo, Uniregistry, Afternic, Flippa etc..
My suggestion would be to drop it or get a refund.. Then read about domains and what sells and not.
gl..