Best lumbar cushion for flying?

For driving, I cut 6 inches off a swim noodle and shove it behind my spine. It's not compactable, but it's light, it works, and losing it is of no consequence.

However, I feel better if I get up and move around.

Funny you should ask. I recently drafted a review of Fitterfirst's ProActive Disc. The primary purpose of this inflatable disc is to give a "Swiss Ball" experience to ordinary chairs. It also works very well as a highly-portable lumbar support for flying and driving. The device was designed by this specialty shop; it's made by Cascade Designs and has the same wonderful oversized valve used on the Therm-a-Rest mattress pads.

The way to use the disc is to fully inflate it, position the pad where you want it, and crack the valve until it's deflated to the desired level. It's pricey but should last forever if treated well. If you do happen to mistreat the pad, you can use the Cascade Designs repair kits to fix it. I also use it when going to events at a stadium for cushioning and to boost my height a bit (yes -- I was that guy sitting in front of you).

One option that's a bit less expensive is the Ledraplastic Overball: a little ball marketed as a play toy about 20 years ago. The balls inflate to a diameter of 7 to 9 inches; they're springy and remarkably strong. Some Pilates instructors started using them as a substitute for Joe's Magic Circle. The Pilates Mini Ball workout is a classic (here's a sample). Colleen Craig's "Strength Training on the Ball" uses a mini ball in tandem with a Swiss Ball for multi-directional destabilization -- a fantastic strength/balance program in a book. After getting noticed, many different manufacturers are making their own balls now: the FitBall Mini, the Fitterfirst Mini Ball, the Franklin Air Ball, and even Leslee Bender's Bender Ball (promoted on infomercials). All of these little balls are are well-made; they are interchangeable. If you hurt after a flight, lying on the floor with an Overball (or one of its imitators) in the small of your back is tremendously relaxing.

[Oliver: feel free to put in the KK Amazon affiliate link for any of those products.]

I'm of similar build, and have been happy how this works for me while flying: a collapsible lumbar support. It's basically two sheets of plastic, and you adjust it by moving the tabs into different slots to make one piece curve. (see photo here: Permalink: http://amzn.com/B00383W5LI) Folds flat so it's easy to store in an outer pocket of your carry-on.

I take Relax the Back's self-inflating back rest pillow everywhere I go, especially traveling. Simply open the valve, and it inflates (and you can inflate it to your desired support, which is great). Close the valve, and it stays put. Then Open the valve and roll up when you are done. It also works as a pillow in a pinch.

http://www.relaxtheback.com/best-sellers/self-inflating-back-rest-rectangle.html

I inherited my dad's back problems, the sort that don't bother you all of the time but if I'm sitting for long periods driving or flying things can get uncomfortable. He introduced me to the McKenzie Super Roll a few years ago and it's pretty much awesome. I keep one in my car all of the time. When flying, I tuck it into my carry on. It's not as small as something you could deflate, but does the job so well that I don't mind.

just a personal experience - i used the Proactive Disc for <2 months, a total of maybe 5 times, and it got a air leak (rip in the edge fabric).