Germanwings crash: What is rapid decompression actually like?

“When it happens you literally feel like the back of the aircraft has exploded"

File photo: Planes are pressurised because humans cannot survive in the thin air of the optimum cruising altitude for airliners (Getty Images)

Rapid decompression of an aircraft is a most terrifying experience – and one that could possibly explain what happened to Flight U49525.

The A320 aircraft descended for eight minutes from its cruising altitude without any indication from the pilots that anything was wrong, a fate that David Learmount, operations and safety editor of Flightglobal, described as “weird”.

But one possible explanation is the sheer violence and terror caused when the cabin suddenly loses pressure.

A user of the PPRuNe aviation forum, called Superpilot, described what happens based on an account of a captain who had experienced - and survived - just such an event.

“When it happens you literally feel like the back of the aircraft has exploded. Your tongue is swallowed by your throat in a second, your ears begin to hurt and teeth become a hundred times more sensitive,” he wrote.

“If you already have an ear infection or a bad filling, you're likely to pass out as a result of the instant pain. None of these can be simulated in a sim or be trained for.

“On top of that, the cockpit fills with a cold mist that freezes the skin. All of these aspects make it incredibly difficult to recognise and reach out for the oxygen mask and autopilot controls.

“Stressing or moving about rapidly to find/don the oxygen mask chews into the time of useful consciousness.”

Planes are pressurised because humans cannot survive in the thin air of the optimum cruising altitude for airliners.

What could have caused the decompression remains speculation at this stage. The plane apparently hit the ground in one piece and there is no suggestion that a bomb was involved.

But what is clear is that part of the safety drill, when passengers are told to “pull the mask towards you to start the flow of oxygen”, does not describe a simple procedure and it is one you should hope never to have to experience for real.