Periscope depth/Crash dive won't work

[Vecna]

Hi everyone, first I like to say that this forum is great and many thanks goes out to the modders as i've gotten a few to improve my experience

Anyway on to my problem that I find critical indeed. Im following my route surfaced when I get an alert about aircraft(s), naturally I then hit P (Periscope depth) or C (Crash dive), tried both several times now. What happens is that someone decides to pull my speed from full/standard down to all stop (using the porpoise class, not that it should matter). Im sure most of the readers already figured out that i've been blown to pieces alot of times because these aircrafts seem to engage surfaced targets 99% of the time

I'm sure it has worked more than once before. Think it did while I ran the tutorial missions and before patching the game at all, atleast P (periscope depth) has worked at some point. The advantage of crash dive is kinda crucial at times but I have been forced to manually set my depth atm and im sure you already figured out that I have been literally blown to pieces because I didn't dive fast enough. Really annoying and I was hoping anyone here might know how to fix this problem?