Your best bet is to find a good aviation tax guy and let them do it for you... there are often flyers hanging in crew rooms around tax time for CPA's that specialize in airline employee taxes.

Some things can be deducted in full, others in part, and some not at all. In addition, if your company pays per diem, there are rules that permit you to deduct the difference between what you get and the standard govt day rate for each city you spend a night in (it's a bit more complex than that...), but can be quite significant, especially if you fly internationally a lot.