The doors aren't jettisonable but they are fitted with MDC (Miniature Detonating Cord) or an LCC (Liniar Cutting Charge) wichever you want to call it! but as we found out in 04, initiating of the MDC under water causes such a pressure wave that it would knock the poor Air Pongo out leaving him to breathe in water for the rest of his days, (wich wouldn't be very long) so a question was asked to the Septics over the pond, "use a knife" was the answer, so they do.