Gannet underwater ejection seat.
Gentlemen I have just discovered this thread so please excuse me for responding to some older comments. Gannet Driver is partially correct about the AEW 3 underwater ejection seat.
In January 1966 the CO 849 invited me into his office. He said 'You have a girlfriend up in Scotland don't you?' I replied 'Yes'. He then said 'Would you like to spend a few days in Scotland?' Of course I said 'Yes', to which he said 'Good, you have just volunteered for the underwater ejection seat trials.'
To cut a long story short, I arrived at a submarine base on the West coast of Scotland a few days later. I was directed to a large hangar-shaped building with a water tank attached to the side. I later discovered that the wall attached to the hangar was actually glass and you could view into the tank. As I trudged through the snow I noticed a diver standing on the top of the water tank breaking the ice with a pick axe. I was issued with a diver's suit and briefed on the seat.
The seat was designed such that when the aircraft sank a barometric device allowed the side windows to implode at a set depth to fill the cockpit with water and equalise the pressure. An explosive charge blew off the canopy and fired the seat up the rails. It was obviously a reduced charge from the normal ejection seat. Once clear of the aircraft the mechanism released the seat harness, inflated the life jacket and released one side of the oxygen mask. An unconscious pilot would arrive on the surface able to breathe and float. I did two runs, a manual activation and an automatic, simulating unconscious, in the icy water. Both filmed from inside the hangar.
The system was subsequently approved, but without the release tube connected to the oxygen mask. An unconscious pilot would arrive on the surface with his oxygen mask on with the end of the oxygen hose in the water! To my knowledge at least one aircraft was fitted with the seat.
For my troubles I have a tie with the Martin Baker triangles on it, with a frogman between each symbol. An exclusive club. The girlfriend. Well, I was on the West coast and she was in Elgin so that was busted flush.