I know its a massive over simplification, but could the black box not be ejected from the plane shortly before/after impact, a small CO2 Canister to inflate an some kind of flotation device would see it bobbing about at least CLOSE to the crash site... It doesnt even need to be the black box.. maybe just a load of small botany transponders released on impact with water?
There must be ways that this could be mitigated in future...
Biting the hand that feeds IT
