I don't fly very often, but the few times I've flown in the last couple years, I've worn a "Just-incase-diaper", and it's saved me every time. There are unknown factors when you fly, that you can't control.
Example 1. Airplane restrooms. Last flight I was on, one of the restrooms wasn't working, which created extra demand on the other one. When I had to "Go Now" (Urge incontinence) there were 3 people waiting for the slowpoke in the restroom. By the time I got my turn, my bladder had already given up, and I was wet.
Example 2. Stay buckled up!! Another flight I was on, we were going thru a lot of turbulence, which caused TWO things to happen... First, the stress made me have to pee even worse than usual. 2nd, the "Buckle UP" lights came on, and we were not allowed to leave our seats!! By the time the event was over, I had lost the fight, and again my diaper saved my dignity.
Example 3. Delays. A few years back, the flight I was on had several delays. First a crew delay, then a storm-related takeoff delay. By the time we were in the air, the 2 hour flight was turning into a 4 hour flight. I was dog-tired when I got on the plane, and I quickly fell asleep once we were airborne. Being as tired as I was, I didn't wake up until we were landing. While I felt rested, I was also wet.
So the question is, which would be more embarrassing for you? Wet pants, or wearing a diaper that no one will likely notice?