In the case of HMS "Thetis", 4 members of the ship’s company, three RN personnel (Lieutenant Woods, Captain Oram and Leading Stoker Arnold) and one Cammell Laird’s employee (Fitter Shaw) successfully used the escape chamber. During the 5th attempt to escape the occupant of the chamber panicked and tried to open the outer escape hatch before the chamber had completely flooded. As a result, the increased pressure outside the submarine caused an in-rush of sea water, thus drowning the escapee. Because the outer escape hatch remained partially open it rendered the escape chamber inoperative, preventing the escape of any other crew members.