I'm glad that this thread happened! I'm heading off on my third overseas tour in a couple of weeks and this time I won't detune. From Australia it's a 24 hour flight so my bass and guitar will spend a lot of time in the air. I always assumed detuning was recommended because that's what I'd been told to do. One time I did forget to detune, but even three weeks later after the flight my Fender P was still in tune.