Commander: Ok Pilot. You're about to face an endless amount of enemies that become more cunning and relentless each time. Because we know that there is no conceivable way to survive and we are running out of time, we have given you a a crappy plane to fly and a few pilots who probably won't last the first wave. Good luck!
Pilot: Can't I just fly away when I'm weak?
Commander: ... It would be too expensive to repair you. We spent the rest of our money making AA cannons to shoot your plane down.