The doomed Germanwings plane may have crashed because the windscreen cracked, causing a sudden drop in oxygen levels that rendered the pilots unconscious, it was claimed today.
Reports circulating on professional pilot forums suggested the black box on the Airbus A320 had been analysed and revealed that a ‘structural failure’ was responsible for the disaster.
Flight 4U 9525 dropped out of the sky and ploughed into a mountainside in the French Alps at more than 400mph yesterday, killing all 150 people board.
In the latest theory to emerge, it is thought the windscreen gave way, incapacitating the pilots and leaving them unable to send out a distress call.
That may explain what happened in what top French official Segolene Royal has described as the crucial minute between 10.30am – when the pilots were apparently chatting away – and 10.31am when contact was lost.
Flight radar data revealed the plane started its nosedive at 10.31am from an altitude of 38,000 feet.
What happens to the body that makes pilots unable to function after a few seconds?
The problem with Hypoxic Hypoxia is the lack of pressure necessary to “push” the oxygen from inside the lungs, through the tissue, into the blood. This process is associated with Grahm’s Law of Diffusion. This law doesn’t care which way the diffusion is happening; it simply takes gas and pushes it across a barrier in the direction of the pressure differential. Holding your breath doesn’t work because you cannot maintain the pressure necessary to keep the oxygen from “backing up” into the lungs and exhaling it.
For this same reason, you need a pressure-demand mask above 40,000′. You could be provided 100% oxygen, it doesn’t matter, it can’t transverse the lung tissue. You need pressure to force it across the barrier.
If the decompression were gradual then the resulting hypoxia would also be gradual and, if there are no obvious automatic alarms on board, possibly would go undetected.
If the decompression is sudden and complete it would forcibly pop your ears (scary, uncomfortable, alarming) and you would probably instinctively attempt to equalize your inner ears by forcibly exhaling (the exact opposite of breath holding, unfortunately!).
Lastly, if the decompression is violent enough the pressure differential between your lungs and the cabin air could be so great that the air would effectively be sucked out of you. Again, going against any effort to hold your breath.
If there was sudden structural failure, the reduction in pressure would cause all the gas in the body to expand.
‘The pilots would have been in pain as their ears and guts burst and they would have been extremely disorientated.
‘The procedure is to get their oxygen masks on as soon as possible as they would only have a few seconds of useful consciousness without it.
‘Then they should have programmed the plane to descend to a random altitude, just to get it going down to where there is thicker air and it’s easier to breathe.
‘Later on, when things are under control, they should have taken the time to refine the figures so the plane levelled off at about 10,000 feet, where they could remain conscious and continue to fly.’
However, the pilots appeared to put the plane into a steep descent but did not update the figures later, he said. This could be because they failed to apply their oxygen masks in time and lost consciousness.
- It is the third serious incident involving the Airbus ‘family’ in six months – two of them fatal crashes that have left more than 300 dead;
- A safety warning was issued last November after a sister plane of Flight 4U 9525 went into a dive over Spain, falling at 4,000ft a minute before the pilot regained control.
The victims are understood to also include 72 Germans, 35 Spaniards and two Americans.
A cracked windscreen theory was being discussed on the Professional Pilots Rumour Network (PPRuNe), a leading online aviation forum, following an anonymous report that the black box had been successfully accessed for information.
The anonymous report on the pilots forum initially appeared on the Aviation Herald forum and is now being widely discussed by pilots online.
Tony Newton has been a commercial pilot flying A320 aircraft for 20 years and is also a Civil Aviation Authority examiner. He said it is ‘entirely possible and plausible’ that the disaster was due to structural damage to the cockpit, possibly a crack in the windshield, as the unconfirmed report has suggested.
