I used to have a Martin Backpacker and it does fit in an airline overhead - I took mine to Hong Kong a few times. However, I would not recommend it - I am mainly a bedroom player but I found the sound really tinny. I eventually sold it and bought a Baby Taylor. I have never tried that in an overhead and the sound is nowhere as good as my full size guitars but it does the job when you are in a hotel room somewhere and you want a quiet strum.

Eric