@n227rv

During WW2, US female pilots were not allowed in combat but flew transport aircraft across the Atlantic. They carried boxes of Kleenex & used those as a pad. When a box had been used, they opened that little window (about 3"x6") on the side of the large window, & jettisoned the entire box over the Atlantic.

@n227rv Second-hand info here, but military aviators sometimes have/had "relief tubes". It wasn't an issue for fighter pilots, because their bladders could generally outlast their fuel tanks, at least before the advent of in-air refuelling.

I once read a sad story about a tail gunner in WW2 who had his heated suit fail, his relief tube freeze up, and ended up needing at least one leg amputated from extreme frostbite.

On the civil aviation side, my former single-engine Piper PA-28-161 had a total endurance of 6 hours to empty tanks, which meant I never flew longer than 4 hours IFR or 4.5 hours VFR (add an hour for preflight, taxiing, and tie-down). Before prostate cancer, my bladder could *just* make it without needing a bottle, though sometimes I ran straight past the check-in desk at the FBO as they pointed me to the washrooms (they're used to that 🙂).

For female pilots, there's something called a "GoGirl": https://go-girl.com/