Airlines are about as close to banks and governments as you get and so you are not logically going to get a better deal from them by paying in BTC.

Look at smaller businesses more removed from the fiat debt slavery bankers cartel and its associates.

I have found that when traveling Bitcoin accepting hospitality businesses tend to be above average in quality- especially food outlets.

Remember there is limited profit motive incentive for most businesses to accept bitcoin and in many cases they are actually risking adverse reactions from both their bankers and customers by accepting Bitcoin. Plus any business that asks their accountant how can I go about accepting Bitcoin is likely to get told its more trouble than its worth due to the tax recording requirements.

Just support businesses who accept Bitcoin and offer equal or better service than average- and remember that's very unlikely to be any business closely associated with the banks and governments...like airlines.