That actually never worked, as no air objects have Passive Sound Levels in the standard database.
Given the fact that the sound engine doesn't make a distinction that I can find between objects underwater and objects not underwater, within the detection max-min of the passive sonar senors, it doesn't seem likely that this feature can be included without significant reworking.
I suppose we could give helo's a low PSL (around 20-40), but then they would behave exactly like quiet underwater objects, and it would mean making the passive sonar heights higher, which would then present the same problem as before.
So, the basic problem here is that the game makes no distinction between water and air as far as passive-sonar detectable sound goes, as far as I can tell. The only way to work around this so as not to produce anything funny in gameplay that is significant, is to lower the max height of passive sonar, as the helo-sonar feature seems a bit more minor than the persistant missle transients or silent missle launches, especially because SCS didn't even make a serious attempt at including it.
PS. I'm feeling better and better about the sonar fix. I think I can send v1.01 to Bill this afternoon, but I'd like to hear back from Amizaur first.
