[NO REPRO] Submarine bug?

[Felcas]

Canary Cage Scenario
Marsopa submarine
Clear Sky, no Rain, Wind/Sea Zero
Forced it to run on the surface to make the diesel work and recharge the batteries.
SUDENLY a sonoboy appeared 1,84nm from my position.
The bug: how in this world a submarine watch staff would not see an Anti-Sub Helicopter just less then 2nm away?
Is that ok? Or there is a bug in here?
Thanks

[mikmykWS]

Any idea what the altitude was? Save game would be helpful or at least telling us what sub and what helicopter.

M

[ComDev]

Are too many variables at play here, need a savegame. Smaller helicopters are only detectable at 1.5nm to 1.7nm so this is perfectly possible.

Tested real quick in-game and everything seems to be in perfect order.

Thanks! [8D]