While aviation people spend a lot of time and energy worrying about how to squeeze fuel burn a bit or if the wings can be bit more carbon fibre, the ultimate customers - passengers - seem to have very different concerns.
Indeed, Gadget Duck's pitch for the $18.95 Knee Defender suggests that passengers don't give a hoot about economy - what concerns them is mere survival.
According to Gadget Duck, by disabling the reclining mechanism on the seat in front of yours, Knee Defender "helps you defend the space you need when confronted by a faceless, determined seat recliner who doesn't care how long your legs are or about anything else that might be 'back there'...
"If the airlines will not protect people from being battered, crunched, and immobilized - very real problems according to healthcare professionals, medical studies, government agencies, and even some airlines - then people need options to protect themselves."
And, according to Gadget Duck, the stylish device violates no US aviation law, as long as it's not used during taxi, takeoff or landing.
This column, it must be said, neither endorses nor discounts Gadget Duck's claims for Knee Defender's effectiveness - but do note, dear readers, that Gadget Duck does not appear to sell any devices to defend against being punched in the face by an irate passenger in the seat ahead.