Can pilots REALLY concentrate at 35,000 feet?
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Can pilots REALLY concentrate at 35,000 feet?
- OK - We all know we need oxygen to think.
- And - we all know airliners are pressurised to 8,000 feet .
- And - we're told that the percentage of oxygen in the air remains the same at sea level as it is at 8,000 feet and it's still the supposed to be the same at 35,000 feet
- And - like me - I bet you've lost the will to concentrate on that paperback you bought at the airport once you're a few hours into the flight at cruise altitude..and like me you're starting to doze off.
- ...So, I just wondered, if you and I are feeling like this - how are the pilots feeling? And if they're feeling anything like me - are they fit to fly the plane? .
Depending on which science paper you read, the actual percentage of oxygen in the atmosphere seems to vary between 21% and 23% - but let's assume it's 23%.- and let's assume that the scientists are right and that the proportion of oxygen really is the same at all altitudes
The snag is that none of this takes into account that what the pilots and passengers are breathing isn't outside air - it's partly recycled air - which has already been breathed in and breathed out a couple of times - with some of the oxygen being absorbed by someone else's lungs before it got to yours.
So does anyone know what the ACTUAL proportion of oxygen is on a plane say four hours into a flight at 35,000 feet? ........I guess it's probably not 23% or even 21% and that's why everyone feels so woozy.. Of course it doesn't matter so much about the passengers. Unconscious is probably the best way to fly. But what's the oxygen percentage up front, on the flight deck?
I'd like to think the pilots were breathing the right stuff and getting their full 23% - but I worry that they may just be breathing the same recycled second-hand / third-hand air as the rest of us. And if so, I think they deserve better than that - for all our sakes..
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I don't think it's an issue tbh. If it was, wouldn't the media have got hold of it before now and predicted scores of aircraft falling from the skies, or being involved in near misses, because the pilots couldn't concentrate?
Put it this way, I am a nervous flyer, but this isn't one of the things that is going through my mind when I board a flight.
I also don't think the cabin altitude/amount of oxygen affects everyone the same. I can concentrate fine on a flight, what gets to me is tiredness. But I also get tired on long car, bus and train journeys so can't really put that down to the altitude, so I'm guessing it doesn't affect me much.
Put it this way, I am a nervous flyer, but this isn't one of the things that is going through my mind when I board a flight.
I also don't think the cabin altitude/amount of oxygen affects everyone the same. I can concentrate fine on a flight, what gets to me is tiredness. But I also get tired on long car, bus and train journeys so can't really put that down to the altitude, so I'm guessing it doesn't affect me much.
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It has to be noted surely that the air in the cabin is not sealed in at the start of the flight, pressurised and then set to remain stag net for the duration of the flight.
The air being used to pressurise the cabin is taken from a section of the engine normally, which is treated (for pressure, temperature and humidity) before being used to pressurise the cabin. Because this is an ongoing process, there are also outflow valves on the aircraft which air flows out of continuously, which is how the cabin altitude is controlled. An outflow valve allow more air to escape than is coming in will depressurise the cabin and vice versa.
Apologies if I have missed the mark here, I just don't feel it is a problem and my (non expert) understanding leads me to believe that there isn't one to be found.
The air being used to pressurise the cabin is taken from a section of the engine normally, which is treated (for pressure, temperature and humidity) before being used to pressurise the cabin. Because this is an ongoing process, there are also outflow valves on the aircraft which air flows out of continuously, which is how the cabin altitude is controlled. An outflow valve allow more air to escape than is coming in will depressurise the cabin and vice versa.
Apologies if I have missed the mark here, I just don't feel it is a problem and my (non expert) understanding leads me to believe that there isn't one to be found.
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I would suggest, Korrol, that you buy a more interesting book so you won't get bored so easily and let your mind wander off in silly directions armed with nothing but misconceptions and assumptions.
I'm not supporting either side in this debate.
A quick Google scholar for "effect of altitude on cognitive ability" shows that some research has shown that altitude can have an effect on some people. The effect varies considerably by person and I can't (yet) find a paper which determines who is most likely to suffer.
Effects of Altitude and Heat on Complex Cognitive Tasks
I suspect the referenced paper took the participants to a higher altitude than 8000ft but given the spread of impairment suggested by the abstract I can't help wonder if 8000ft might restrict the cognitive ability of some people.
Can anyone point at research which is more aviation oriented?
A quick Google scholar for "effect of altitude on cognitive ability" shows that some research has shown that altitude can have an effect on some people. The effect varies considerably by person and I can't (yet) find a paper which determines who is most likely to suffer.
Effects of Altitude and Heat on Complex Cognitive Tasks
I suspect the referenced paper took the participants to a higher altitude than 8000ft but given the spread of impairment suggested by the abstract I can't help wonder if 8000ft might restrict the cognitive ability of some people.
Can anyone point at research which is more aviation oriented?
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Two other points:
1) Most modern types provide fresh air to the flight deck, it does not come from the re-circulation manifold
2) Air crew develop higher levels of red blood cells due to working long periods of time in a hypoxic atmosphere. Red blood cells carry oxygen around the body, and so the increased oxygen percentage compensates for the outside air.
35,000ft is only a problem when the pressurisation goes pop - at 35,000 feet you have 30 - 60 seconds, but just 5,000 feet higher at 40,000 feet that figure drops to about 15 - 30 seconds...
2) Air crew develop higher levels of red blood cells due to working long periods of time in a hypoxic atmosphere. Red blood cells carry oxygen around the body, and so the increased oxygen percentage compensates for the outside air.
35,000ft is only a problem when the pressurisation goes pop - at 35,000 feet you have 30 - 60 seconds, but just 5,000 feet higher at 40,000 feet that figure drops to about 15 - 30 seconds...
Stirring the pot a bit, it gets worse:
Although the partial pressure of O2 is 21% of air pressure, due to expired CO2 and H2O vapour, the alveolar PPO is only 14%.
At sea level the alveolar PPO will be about 106 mmHg. at 8000ft: 79 mmHg and, at 4300m: 62mmHg (The research referred to used 4300m 14,100ft)
I've skied at 12,000ft but wouldn't want to hang about at 14,000ft for an extended period.
The mechanics of oxygenation are not linear. As the pressure reduces above 20,000ft then the ability of haemoglobin to transport O2 is diminished introducing a further problem. Like most RAF pilots I've had a demo of hypoxia at 25,000ft. It is insidious and one goes bye-byes with no warning (well, not to the subject who thinks he's doing just fine).
Anyway, getting back to 8000ft:
Perhaps, but professional pilots are closely monitored with regular medical checks. Back in the day, we were made aware that smoking could have an adverse effect upon oxygenation. I don't know whether that effect is significant or not.
Could be the glass or three of wine with lunch 
Although the partial pressure of O2 is 21% of air pressure, due to expired CO2 and H2O vapour, the alveolar PPO is only 14%.
At sea level the alveolar PPO will be about 106 mmHg. at 8000ft: 79 mmHg and, at 4300m: 62mmHg (The research referred to used 4300m 14,100ft)
I've skied at 12,000ft but wouldn't want to hang about at 14,000ft for an extended period.
The mechanics of oxygenation are not linear. As the pressure reduces above 20,000ft then the ability of haemoglobin to transport O2 is diminished introducing a further problem. Like most RAF pilots I've had a demo of hypoxia at 25,000ft. It is insidious and one goes bye-byes with no warning (well, not to the subject who thinks he's doing just fine).
Anyway, getting back to 8000ft:
I can't help wonder if 8000ft might restrict the cognitive ability of some people
everyone feels so woozy..
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You'd kinda figure that something as basic as this would have occurred to someone other than the OP at some time previously in the 100 years of the most researched industry ever...As if the percentage of O2 could vary with altitude and as if the pressure wasn't the critical thing? Don't they teach science.... no, sorry..
Where do people get these bizarre ideas about recirculated air being somehow inferior? The Daily Wail I suppose. Well, that's proof then.
When Stevenson said his Rocket could do 30mph there was a belief that people couldn't breathe at such prodigious speed and would suffocate. We haven't progressed much when it comes to swallowing baseless mythology, have we?
Where do people get these bizarre ideas about recirculated air being somehow inferior? The Daily Wail I suppose. Well, that's proof then.
When Stevenson said his Rocket could do 30mph there was a belief that people couldn't breathe at such prodigious speed and would suffocate. We haven't progressed much when it comes to swallowing baseless mythology, have we?
Last edited by Agaricus bisporus; 29th Jul 2012 at 11:56.
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Can pilots REALLY concentrate at 35,000 feet?
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Spare air bottle
I always use mine above 45,000 ft, as it helps me concentrate on the Times crossword.
Impossible without the extra O2.
I also try to get the high O2 water from First Class.
Impossible without the extra O2.
I also try to get the high O2 water from First Class.
Anyway they only have to do anything on climb out and descent so don't see the issue providing coffee is on hand. As long as they can follow some magenta coloured thing I am assured the plane flies itself.
Last edited by Mr Optimistic; 29th Jul 2012 at 15:06.
Paxing All Over The World
When weboard a flight, we know that we don't have to work, We may have just finished a day's work. The crew (flight and cabin) get on boar knowing they have to work. So they tend not to doze whilst reading their books. Of course, fatigue is another issue.
I'm self employed and some days, like everyone, I feel rather disinterested in going to work. But I know that the moment I start the car to drive to my client and do what they are paying me to do? I'm wide awake.
I'm self employed and some days, like everyone, I feel rather disinterested in going to work. But I know that the moment I start the car to drive to my client and do what they are paying me to do? I'm wide awake.
As someone that's spent some time in the cockpit at FL410, I don't think the wooziness is related to the air circulation at all. The air always seems fine up there. No mid-flight sleepiness. Keep in mind that what you experienced could be related to a lot of different things, including fatigue, boredom, dehydration (I drink sooooo much water on planes because of this). I'd suggest getting a good book, drinking a lot of water, and taking a nap if you feel tired.
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Indeed one might think that, but many's the time a new insight into an age-old problem has been accompanied by the phrase "Why did no-one ever think of this before?"