This question already has an answer here:
A recurring theme I come across is how, in an emergency, it is safer for a passenger craft (such as an Airbus) to try to land on the ground rather than at sea. My understanding is that the main reason for this is that at the high speed at which the plane would be travelling, landing in the sea would be like hitting concrete and basically break the plane up and kill most of those on board.
But if speed is the issue then why cannot a passenger craft just have a large parachute at the back that is deployed when the plane is say thirty to fifty feet or so above the sea surface so that the speed is drastically reduced (at a carefully pre-calculated rate that is safe for all on board, who would in any case be fully prepared for the landing), at which point the plane would essentially just guide gently into the sea at a speed maybe equivalent to that of a fast speedboat? To be clear I am talking about a parachute that is just intended to add drag and slow the plane down.
Would this work in practice, and if so why don't planes have such a parachute as standard?