I just received a Les Paul and in a gig bag as a gift before a flight.
Anyone ever fly regularly with your guitar as a carry-on?

This is on a 737-800 in the US and I'm a frequent flier which gives me some priority boarding and seat choice.

Am I asking for trouble or would it actually fit in a bin possibly?

Are you on the plane yet? There's usually a tall closet for people with business suits and stuff. You can always ask the flight attendant to put it in there. I wouldn't put it in the overhead bin with all those cranky passengers shoving and jamming their shit up there.

Also not sure if its a grandma's myth or what but I also hear it's good to slacken your strings before a flight - the dryness, pressure or whatever can have an effect on your neck. Can anyone confirm this? Any road warriors out there?
I don't bother slacking strings before a flight.
There are a LOT of overhead bins that are too short to accommodate a guitar. Measure your guitar accurately and call the airline well before you fly to see what options are available. Gig bags are problematic because they provide no resistance to *bending* pressures; you can definitely end up with a broken guitar if it's stuffed in. If you have a Les Paul (or similar guitar with the same headstock angles and specs) you should know that Gibson-style headstocks are the most broken. This is especially important if you're asked to check your guitar before the flight (sometimes airlines will do this at the last minute). Baggage handlers do not treat guitars well.
Made it ok. Closet was denied but overhead bin was actually just right fit. Flight was not full so had the whole bin.
I wondered about this - why did they deny you the closet I wonder -
Would suck to have that expecation and then get denied
Quote by dspellman
I don't bother slacking strings before a flight.

It wouldn't matter in the cabin, but Qantas recommends slackening the strings, at least on acoustics if they are going in the cold baggage hold. In fact, I've been reminded of that at check-in on a few occasions.
If your LP is going in the cargo hold in a gig bag, it may be coming out as mulch whether you slack the strings or not. I'd be pretty nervous flying without a hard case for anything with that headstock. Glad you got lucky with an overhead, but I wouldn't expect to be able to keep it in the cabin every time.

There's a bit of a quandary there. Do you go gig bag and hope it will be accepted as cabin baggage, or do you just put it in a good hard case and assume it will go as hold baggage? I've been around the world a few times with acoustics and always checked it as hold baggage. Airline policy may be a bit easier now on cabin baggage than when I was doing a lot of flying. I never had a problem, except when some thoughtful handler put it in the fragile lift instead of on the carousel, I thought I had lost it. I knew where to look when It happened thereafter, in fact I asked them to put fragile tape on it at check-in.
Hard case 100% IMO. I don't think you can count on being able to keep it in the cabin, and there's no way I'd let a Gibson headstock get checked in just a gig bag. In my mind your only real option is to get an ATA case and either try to carry it on as your only item (off-peak travel times) or just go ahead and check it ahead of time.

With a tele, sure, decently padded gig bag and cross your fingers you don't have to check it. It will at least survive if it has to be checked. But with a Gibson, it's russian roulette. If it goes into the hold without a hard case it's probably not coming out alive. With a gig bag, there's a fair chance of a total disaster. With a hard case, there's more hassle but the odds of coming home with an armful of firewood are really low.