>>>BUT... assuming it hit very hard into "something"... how could it be survivable for the "other" plane ?!
Might not have been. Had they collided with a drug runner (one untracked be DEA or otherwise undetected by ATC), it's conceivable that they too could have gone into the drink, and may not have been found to date.
Just speculation, mind you, but it does make one wonder where the red paint -really- came from....