The title question is what prompted me to post this here for future searchers looking for the answer:
Southwest Airlines informs upon inquiry that they allow carry-on of any “luggable” instrument so long as (a) there is available bin space, and (b) the instrument is in a SOFT PADDED CASE that fits in the overhead bin (SW is flying larger 737-400s these days, and the o’head bins are a lot bigger than they were a few years ago).
If (a) fails to be the case, you may gate-check the instrument (i.e. the flight attendant takes it from you just before you board the aircraft, and returns it to you as you step off at the end of the flight, so the “baggage apes” never get their paws on it.
Anyway, this has been great for carrying my gig-bagged Cort Parlor guitar back and forth between Houston and Tulsa these last couple of weeks.
—found originally here
I’ll see if this answer remains true when I fly on a SWA flight on Thurs with the guitar that my bro gave me.
Greetings from Texas!
Note from after the flights:
I boarded two planes with my guitar in a soft-shell pack with no problems. I just put it in the overhead bin (fit easily with lots of room) and was never hassled at any point during the process.