I remember that I looked to buy an airline ticket with bitcoin a while ago (3 years ago, maybe), but I didn't because it was more expensive. I don't remember what website I used to reach that conclusion, though. I also remember trying Expedia a few times, but there was no Bitcoin payment option when I bought my tickets there. So I had forgotten the idea of using bitcoin to buy flight tickets.
I was buying a ticket earlier today, and I wanted to use a debit card from my bank in Montenegro. Guess what, it failed. There was some kind of confirmation requested after I filled the form with my card number. I should have received a text message I believe, but I didn't. So I went back to the page with payment options, and I was surprised to see a line with Bitcoin, so that's what I choose, and it worked.
Remember that: my card didn't worked but Bitcoin did. With Air Baltic. Congratulations Air Baltic!