Many years later from this thread:
Gunship 2000 chatter

I am having exactly the same problem as Jamon. Everything works well after I wrote the command KEYB US in the dos box file (I am using a spanish keyboard) but in the middle of the flights, normally when engaging multiple enemies and getting some damage, all the keyboard but the arrow keys gets blocked, it does not work anymore.... cyciling is at 6000 I think.. any idea pals? Love the game!