Air dropped depth charges are already in the game, and if you dive, planes will already attack your last known position and drop their bombs/DC's. In this case you'd prefer them to have bombs
edit - assuming your using my attack mod
This is just one of my little side projects while I wait for the next patch before I go back to the attack mod. Tho some of my projects are going to be part of it.
When I was testing with that merchant they never scored a hit .. but later on I got a nice solid hit on the Bismark with one.. not in the rudder.. maybe next time
As far as having to get the planes to line up .. etc etc .. the devs already had most of this in. I think they just gave up part way through.