G forces
When we did our ditching training in the SVC10, we were afterwards shown a film of a 10 foot SVC10 model, specially built to simulate a ditching. Every time it was catapulted into the tank, the model`s nose area underwent violent pitching. The boffins calculated that those G forces would have killed the cockpit crew in the event of a real ditching. The injury would have been the tearing of the arteries from the heart. So Turkish hitting tail first, then violently pitching down, then the sudden stop, may well have done just that.