Musical instruments are permitted as carry-on or as checked baggage. To assist passengers traveling with instruments the TSA partnered with musical organizations around the country to understand the challenges of transporting musical instruments. The following recommendations result from these partnerships and are provided to assist musicians:

* It is always important to check with your air carrier prior to transporting your instrument. TSA is concerned with screening the instrument while the air carrier determines whether an instrument meets the size requirements for their aircraft.
* Horn instruments are best transported as checked baggage.
* String instruments, within carrier size limitations, are best transported as carry-on items.
* Checked items that are fragile or need special handling should have short written handling and repacking instructions placed within the case where a screener will take notice. Such instructions should be very clear and understandable to someone with no musical background.

My thoughts:
Last time I checked LAX had a shield that didn’t allow even a small guitar case to go through. I haven’t even looked closely in a while, because once I almost go stranded I figured I should not take a chance again.
It’s worth trying to board with the guitar again, because my setup with the guitar case inside a flight case weighs 69 lbs and since the weight limitation was changed to a maximum of 50 lbs. a couple of years ago, I have had to pay overage charges and those are very, very erratic. Some people let it slide, some people charge $50 and others charge $250 overage charge.
I very much doubt that any guitar fits into the tiny overhead space on the popular Brazilian jets.
Thanks Michael B.