I haven't flown with my instruments in a long time but even then, I did it infrequently. That said, I always look to see whether my guitar (acoustic) or bass would fit in the overhead and I pay attention to other instruments boarding. I flew across country and back over the past few weeks, Southwest, and boarded early enough that all 4 legs, I could have easily put my bass in the overhead. I saw one guitar and a violin on one of the flights. Depending on the depth of your bag, I would expect that it would fit in most planes' overhead bins.
As was said, the TSA has ruled that instruments can go onboard at the discretion of the flight crew. So the advice of being early, friendly, as accomodating as you can be (if you are trying to carry on a bass, don't bring any other carryon baggage with you) and ready for other possibilities (like gate check) should be taken seriously.
Personally, I've been very interested in the SKB ATA case that you put your gig bag inside. Back in the day when I was playing on the acoustic circuit, lots of the heavy touring players put their guitars in a Calton for flights and checked it. They put their clothing in a gig bag for the flight and then switched the guitars and the clothing when they arrived at their hotels.
As was said, the TSA has ruled that instruments can go onboard at the discretion of the flight crew. So the advice of being early, friendly, as accomodating as you can be (if you are trying to carry on a bass, don't bring any other carryon baggage with you) and ready for other possibilities (like gate check) should be taken seriously.
Personally, I've been very interested in the SKB ATA case that you put your gig bag inside. Back in the day when I was playing on the acoustic circuit, lots of the heavy touring players put their guitars in a Calton for flights and checked it. They put their clothing in a gig bag for the flight and then switched the guitars and the clothing when they arrived at their hotels.