I take a plane 2-6 times a week and been wearing the freestye libre since January 2015. The frestyle libre sensor has so far not a single time made the airport security screening scanners go off when you walk through the metal detectors. I tend to recall some references in the manual about not using the reader device during air transportation. Reason being its a radio transceiver and could interfere with plane/navigation electronics. Been discussing it with a couple of pilots, who mainly said everything was overstated, as such medical devices approved for general market usage in US and Europe would be safe, and allowed when in midair. Mind you, the reader also need to be within just a couple of inches for the signal to be strong enough to read from the sensor, so total signal strength is bound to be very very low.
Have tried wearing my sensor in a sauna and it stayed on fine as well as when doing water sports. I actually have only the experience with it, that I find it quite hard to get it off again. While I do recognise other fellow users have reported about sensor falling off more or less by themselves. Only thing I make sure of when inserting it is that the skin is totally clean, has been swabbed with the disinfectant and then totally dry as possible before placing the new sensor on. I also press quite hard onto it when placing it, maybe for like 25-30 seconds. And ups yes, I also do shave the skin clean with a razor before placing it. Not sure if shaving makes a difference in helping it to stay on for full 2 week duration, but it does make a huge difference in 'manly pain' when pulling it off again.