"You should never fly through a thunderstorm in peace time"
There is a funny story that reveals a great truth here.
It may or may not originate with the USAF 555th Fighter Squadron.
Above the squadron operations desk at their home base in Arizona in 1965, a sign: "There is no reason to fly through a thunderstorm in peacetime."
Above their squadron operations desk in Udorn, Thailand, in 1966: "There is no reason to fly through a thunderstorm."