There may be a topic already that covers this. If that is the case this can be shut down.
Recently, I have seen a bigger number of people saying that their app crashes on long haul flights. I am going to list some things that may help especially for iPhone users.
Turn view to Scenic - this will help keep the app moving lowering its ability to crash
Turn time to night - this always seems to help
Unplug and then plug back in - this will keep the device moving also as stated in the first (On overnighters keep it plugged in at all time)
Turn graphics to the lowest setting - this will keep the game smoother (especially for iPhone)
Turn off HUD
Turn “Anti Aliasing” off
Lower your screen brightness
Turn on low power mode
Restart device before every flight
Also, newer iPads are really good for Long hauls and Ultra Long hauls.