Thursday, July 05, 2007

Deep Breaths Please

Looking at the dramatic Daily Mail story of passengers on an Easyjet flight to Malaga, fearing that they would die, as it, "Plummeted" 20,000 feet, here's why the Oxygen masks in the aircraft, releasing in the passenger cabin, shouldn't provoke immediate panic.

The masks will appear automatically if the cabin pressure drops below a certain level. Without that necessary pressure, which is normally maintained at around 8,000 feet, your body won't be able to use the Oxygen in the air to stay conscious, which is why high-flying passenger aircraft are equipped with Oxygen masks, to deliver a higher proportion of the vital Oxygen your body requires for the period of time that the pilot will need to take the aircraft down to 12,000 feet, where you won't be struggling to breathe.

So, if there's a sudden pressurisation problem, the pilot will try and take the aircraft to a safe level as rapidly as possible in a safe but very rapid descent, which is uncomfortable and worrying for the passengers but is not dangerous.

This is a very rare occurence, given the millions of passenger flights that take place but if it ever should happen to you, now you know.


Anonymous said...

At least if it all works as intended.
Recently I was involved in a crash investigation you may remember hearing about where a Learjet departed Sanford Florida,lost radio contact, when fighter jets were scrambled to take a look at the Learjet which had climbed above its correct altitude they couldn't see in as the windows were frosted, the Learjet carried on flying until it ran out of fuel.
It was found that the probable cause of the accident was sudden depressurisation for an unknown reason ,unfortunately the emergency oxygen control valve was possibly in the off position, the oxygen bottle was probably empty as it hadn't been serviced since a previous deployment and proper maintenance records had not been kept.
Analysis of the last radio messages indicated that the pilots were not wearing oxygen masks at that time.
Yes, of course they all died.

DrMoores said...

There's a coincidence, I covered the flight you mention and the recent Helios 737 tragedy for Sky News.

At that kind of height, you've only 40 seconds or so of useful consciousness or in the case of the Helios 737, the pilots continued to climb while they questioned the low pressure indication warning alarm, with the result that they rapidly succumbed to hypoxia before they understood why they had a problem.

Mr Friday said...

I think the scariest thing about travelling wirh Easyjet is the length of the queues at the check-in desks.

Anything that happens in-flight is a minor irritation by comparison.

Anonymous said...

The FAA rules now state that the first thing you must do as pilot / copilot if you hear the low cabin presssure alarm is to put on your oxygen masks, then you can think about why its gone off.

DrMoores said...

Absolute common sense and I think the same is true in JAR OPS but this appeared to have been a rather laid-back Cypriot carrier.

Anonymous said...

Whilst the emergency is being responded to it would be less scary for passengers to be told what is happening in calm clipped tones from a pre-recorded message that hits in with oxygen mask drop. Not knowing whats happening is sufficient for us lesser non-aviation mortals to prepare to meet our Maker!

DrMoores said...

That's probably a good idea, although I suspect the surrounding noise and sense may nake it difficult to hear.

This is a remarkably rare occurence and of course, it's provided for in the safety briefing in a limited way as airlines don't want to frighten passengers. The pilots don't have time or the ability to broadcast once they have their oxygen masks on, as the priority is to get the aircraft to a safe altitude as rapidly and as safely as possible.

Anonymous said...

anon again!

I think I might be led to think I was taking part in some death ceremony if I fell just over 4 miles in a few moments. No wonder they was panic and dismay up there.
Thank goodness the crew were able to keep an element of control.

Jeremy Jacobs said...

Malaga awaits on July 30th. Ryanair or BA instead?