I had FinnAir crush the head tube on a *new* frame. I was compensated for the full amount with very little hassle. I think the key to making it a smooth process is going to the airline office in person, things seem to move much quicker that way.
1) I went to the local FinnAir office with the damaged frame and spoke to them about it.
2) As per their request I went the the LBS and got an official letter that said the frame was destroyed.
3) Took the LBS letter and copies of the receipt to FinnAir.
4) in about a month or so the money was transfered to my account.
All this was two years ago. I hope this helps.