I read an accident report a few years back where a double engine failure (caused by fully closing the wastegates of a naff RayJay turbo system and briefly attaining stratospheric power before jettisoning the molten cylinders down the exhaust pipes) ended in a frozen lake and sinking. The engineer - who was along for the ride - kicked the co-pilot's window clean out and they were able to escape. All the more amazing was the fact that this was a pressurized twin (might've been an old 340) with seriously beefy windows.
The body is capable of some amazing stuff when under duress dontchathink?
I'd have thought that some kind of pointed escape hammer would be useful for such an event.