Luckily, I’ve got elite FF (frequent flyer) status and usually have no issues stuffing acoustic guitar semi-hard case (sometimes electric/variax gig bag) in overhead or vertical closet with FA (flight attendant) permission.
More often, Variax rides in Pelican ATA roller case checked in cargo hold. Main question: "is that a firearm?" LOL...
BUT remember to remove any battery packs and that includes legacy Variax with Alkaline bricks or JVT’s with Lithium pack. I even printed a page slipped under strings for TSA which reads “NO BATTERIESâ€, please latch case carefully…
I also do this for my pedal board which doesn’t normally carry batteries installed in most pedals but every once in a while I forget a 9V or something that got left in a pedal while testing, etc.
I don’t think TSA’s too hard core about small Alkaline cells but I don’t give them any reason to tear into my gear when checked through to destinations.
All my battery packs including Alkaline travel as carry on inside an RC Lipo fire-resistant charging bag. Tape or plugs over any bare metal contacts. At most airports best to take them out of your carry on bag and place them in a tub for Xray screening.
TSA allows unlimited number of Lithium chemistry in carry on luggage IF each pack is less than 100Wh. Multiply V x Ah to determine Wh.