Modifying visual detection
 

Recently, as I'm getting back into Silent Hunter 3, I've run in to a kind of infuriating issue where my crew simply do not notice enemy planes until they're already dropping their payload on me. I've been mostly lucky that they've missed most times, but the times I don't get lucky it ends my little type II on the spot. Is there a way I can tweak how quickly they see things?

SH3 is a bit dumb about time compression. If set to 1024x the crew take the opportunity of dozing off for about five minutes at a time because they know the Kaleun is not paying attention.
With excellent or moderate visibility I can get away with 256x and still get under in good time except sometimes for some fast fighter aircraft. As the weather gets worse I can get away with less, but the aircraft appear less often. The real killer is fog/rain, as surface escorts with radar can appear at short range out of nowhere and kill me before I have a chance to do anything. When the visibility is "zero" I spend as much time as possible submerged.