I was based in Ruacana from Oct 1980 to April 1981 and everytime the guys let loose at the airbase, we had to fall into the foxholes (ours was a massive big hole dug underneath the foundations of an old house
The mortars would let loose from our side and I remember also the first night almost loosing control of my bodily functions.
At the end the mortars (which were about 30m from our tent) could fire as much as they liked, they did not wake me anymore