Hi Brit
I have found my planes running out of fuel at times.
It seems to be when you patrol them beyond limit, with them to land at a nearer base.
If they encounter an enemy patrol they will follow and then not make it to the new base, but rather try for home!
Doesn't seem to matter what orders you give them.
Something to look at for your next patch - once you've finished programming an AI thats acceptable to NASA and more importantly, 'BillyNoMates' lol