Crash after loss of conciousness
That would be the second SE oxygen related crash in a short period of time:
ERA09FA429
ERA09FA429
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B2N2
Very Sad reading this report. What a shame he never used the shute when things got bad.
Interesting on our last discussion on pilots passing out at 25000 feet was that he survived nearly an hour in reduced control of his aircraft at altitudes up to 26000 feet and most of that time at 25000 feet and managed ATC communications albeit confused.
What is abvious is that up to 20K you have a reasonable chance if you dont smoke and are in reasonable nick over 20K and your on a slippery slope if the oxy system goes wrong.
Pace
Very Sad reading this report. What a shame he never used the shute when things got bad.
Interesting on our last discussion on pilots passing out at 25000 feet was that he survived nearly an hour in reduced control of his aircraft at altitudes up to 26000 feet and most of that time at 25000 feet and managed ATC communications albeit confused.
What is abvious is that up to 20K you have a reasonable chance if you dont smoke and are in reasonable nick over 20K and your on a slippery slope if the oxy system goes wrong.
Pace
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If these are what "we" think they are, i.e. oxygen failure without the pilot realising it, maybe the problem is that some pilots are flying without monitoring their oxygen levels.
It is probably easy enough to lose oxygen without realising it.
That 737 over Greece managed it perfectly well without either "professional" pilot suspecting a thing, despite cabin altitude warnings going off everywhere.
In a GA cockpit, in an old-style fitted system (as is typically found in turbocharged planes) the cannula or mask just plugs into a bulkhead-style connector / variable-orifice flow restrictor, which is fed with a constant pressure (about 20psi) from a first-stage regulator which is located somewhere near the cylinder in the boot. If you stop sucking the oxygen, there is no warning.
And most turbocharged pilots will just be using the default provided system. I bet most of them will have never heard of anything else. This may be more true of the Cirrus customer base, due to their innovative (not intending this in any sarcastic way) marketing.
With the Mountain High electronic demand reg, if you stop breathing, after a while you get an audio warning, but if you merely breathe lazily (which at 25k won't be good enough) you won't get the warning.
With the Precise Flow demand reg (which I have) you hear only the distinct hiss of the oxygen pulse as you inhale, but there is no warning as such if you stop breathing.
This kind of thing could get any of us, and could catch anybody flying at 25k in one of the old-style fitted oxygen systems unless they watch their blood oxygen level carefully.
The problem is they have no backup - other than a rapid descent which isn't going to be an attractive option if there is nasty stuff below, which is probably why you were at 25k in the first place
I don't have a backup for a first-stage regulator failure for example... it's not really practical.
It is probably easy enough to lose oxygen without realising it.
That 737 over Greece managed it perfectly well without either "professional" pilot suspecting a thing, despite cabin altitude warnings going off everywhere.
In a GA cockpit, in an old-style fitted system (as is typically found in turbocharged planes) the cannula or mask just plugs into a bulkhead-style connector / variable-orifice flow restrictor, which is fed with a constant pressure (about 20psi) from a first-stage regulator which is located somewhere near the cylinder in the boot. If you stop sucking the oxygen, there is no warning.
And most turbocharged pilots will just be using the default provided system. I bet most of them will have never heard of anything else. This may be more true of the Cirrus customer base, due to their innovative (not intending this in any sarcastic way) marketing.
With the Mountain High electronic demand reg, if you stop breathing, after a while you get an audio warning, but if you merely breathe lazily (which at 25k won't be good enough) you won't get the warning.
With the Precise Flow demand reg (which I have) you hear only the distinct hiss of the oxygen pulse as you inhale, but there is no warning as such if you stop breathing.
This kind of thing could get any of us, and could catch anybody flying at 25k in one of the old-style fitted oxygen systems unless they watch their blood oxygen level carefully.
The problem is they have no backup - other than a rapid descent which isn't going to be an attractive option if there is nasty stuff below, which is probably why you were at 25k in the first place
I don't have a backup for a first-stage regulator failure for example... it's not really practical.
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other than a rapid descent which isn't going to be an attractive option if there is nasty stuff below, which is probably why you were at 25k in the first place
You have to question why a pilot would want to struggle up to FL250 in the first place in a non pressurised piston single.
In Europe even over the Alps you wouldnt need FL250 to cross the Alps other than in strong winds.
The usual reasons are crossing high mountains, clearing weather although FL250 wont get you on top of a lot of Cbs. Getting above the icing levels in the summer months. In winter FL180/190 would do that. Staying in certain airways. Getting the best tailwinds? maybe. Clearing turbulent layers (maybe).
Really unless I am missing something there are not many occasions where FL180 one way and FL190 the other wont achieve what you want in an unpressurised single engine piston.
At those levels you shouldnt come to much harm on oxygen even if the system or supply failed.
Pace
I'm still concerned about the attitude/belief that up to 20,000 feet you have a reasonable chance. Incorrect.
There's a great article to read here:
SKYbrary - Hypoxia (OGHFA BN)
In particular, I'd like to emphasise the following:
Also note that the Time Of Useful Consciousness tables are for Rapid Decompression cases, and do not include the scenario of climbing to altitude with the gradual degredation of oxygen throughout the climb. Pilots can pass out during the climb to height !!
There's a great article to read here:
SKYbrary - Hypoxia (OGHFA BN)
In particular, I'd like to emphasise the following:
Critical Stage, above 5,500 m (18,000 ft)
Above this altitude, complete incapacitation can occur with little or no warning. All senses fail, and a pilot will become unconscious within a very short period of time. No stimuli such as the radio will be able to help a pilot suffering from hypoxia, especially fulminant hypoxia, above 5,500 meters (18,000 feet).
Above this altitude, complete incapacitation can occur with little or no warning. All senses fail, and a pilot will become unconscious within a very short period of time. No stimuli such as the radio will be able to help a pilot suffering from hypoxia, especially fulminant hypoxia, above 5,500 meters (18,000 feet).
Also note that the Time Of Useful Consciousness tables are for Rapid Decompression cases, and do not include the scenario of climbing to altitude with the gradual degredation of oxygen throughout the climb. Pilots can pass out during the climb to height !!
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Pace,
The tongue in cheek reply would be that the sales brochures for all these planes quote the fantastic headline TAS figures at FL250, so the pilot was only doing that, and doing it within the certified envelope 
The sensible reply might be that if you really like cruising at 75% to 85% power, and are aware that your engine probably won't make TBO (few turbo engines do), then why not? You get the highest TAS up there. A lot of SE pistons do 200kt plus up there. I think even the TB21 almost does that, somewhere above FL200. The oxygen usage will be high but we don't know how often he was doing this; probably not often.
It is true that stratus cloud is very rarely above FL180. But the other week I did a 6hr20m flight (UK to Croatia) wholly at FL180/FL190 just to stay on top, and there was no frontal weather around. FL160-180 is pretty common.
A lot of warm front weather has tops close to FL250. I always cancel those flights.
FL250 capability would be dead handy to have, and would improve my "despatch rate" from say 75% to maybe 90% because most warm fronts can be crossed at FL250. Not CBs of course but the whole idea of flying high is to be VMC on top so one can visually avoid anything sticking up.
The only reason I have not bought a TB21 yet is because due to the lower compression it is about 10% less efficient (MPG) which impacts the range, and if I fly it "as intended" it won't make TBO i.e. 10 grand to pay at the halfway stage. Plus the lower payload... plus some engine downtime stories due to turbo issues...
It is true that Eurocontrol routings get a whole lot more interesting at FL200+ (upper airways are a lot more straight). I have never filed that because at FL200 I have to run at max RPM so the SFC is not as good as FL180. But these accidents were in the USA where they don't have this stuff.
If you have a tailwind, sure. But it doesn't improve much from say FL180 to FL250.
Just unstable weather, and less than violent frontal weather.
I think one would have to make some fast decisions though.
There are passengers too, possibly.
You have to question why a pilot would want to struggle up to FL250 in the first place in a non pressurised piston single.
The sensible reply might be that if you really like cruising at 75% to 85% power, and are aware that your engine probably won't make TBO (few turbo engines do), then why not? You get the highest TAS up there. A lot of SE pistons do 200kt plus up there. I think even the TB21 almost does that, somewhere above FL200. The oxygen usage will be high but we don't know how often he was doing this; probably not often.
In Europe even over the Alps you wouldnt need FL250 to cross the Alps other than in strong winds.
A lot of warm front weather has tops close to FL250. I always cancel those flights.
FL250 capability would be dead handy to have, and would improve my "despatch rate" from say 75% to maybe 90% because most warm fronts can be crossed at FL250. Not CBs of course but the whole idea of flying high is to be VMC on top so one can visually avoid anything sticking up.
The only reason I have not bought a TB21 yet is because due to the lower compression it is about 10% less efficient (MPG) which impacts the range, and if I fly it "as intended" it won't make TBO i.e. 10 grand to pay at the halfway stage. Plus the lower payload... plus some engine downtime stories due to turbo issues...
Staying in certain airways.
Getting the best tailwinds? maybe.
Really unless I am missing something there are not many occasions where FL180 one way and FL190 the other wont achieve what you want in an unpressurised single engine piston.
At those levels you shouldnt come to much harm on oxygen even if the system or supply failed.
There are passengers too, possibly.
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What kind of an oxygen system does the SR22 have? Is it constant flow, or with a demand reg?
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The comments up to FL200 meant in comparison to FL200 up to FL250.
I would rather have an Oxygen failure below FL200 than above
At FL180/190 if your oxygen supply failed you would stand a reasonable chance of being wired up well enough to descend to more favourable levels.
I am not a scientist but would imagine that if you are reasonably fit your not going to black out at those levels over a short time and should have enough brain power to get the aircraft down in reasonable shape. If you do black out after a short period something is seriously wrong. I knew a Glider pilot who had problems at 8000 feet but then he puffed through 40 fags a day.
In the accident report on the Cirrus above the pilot lasted nearly an hour at FL250/260. How would he have been at FL180/190?
Life is a risk and the only way to avoid that risk is to refuse to fly at levels where you need an oxygen supply. Any level over the universally accepted 10000 feet (Americans say higher) is a risk and mechanical things do break or go wrong.
Maybe any high level flights in non pressurised aircraft with oxygen should be avoided until more fail safe methods of supplying oxygen and monitoring the oxygen transfer are invented.
Otherwise we either take a risk or stay at home in bed.
Pace
The comments up to FL200 meant in comparison to FL200 up to FL250.
I would rather have an Oxygen failure below FL200 than above
At FL180/190 if your oxygen supply failed you would stand a reasonable chance of being wired up well enough to descend to more favourable levels.
I am not a scientist but would imagine that if you are reasonably fit your not going to black out at those levels over a short time and should have enough brain power to get the aircraft down in reasonable shape. If you do black out after a short period something is seriously wrong. I knew a Glider pilot who had problems at 8000 feet but then he puffed through 40 fags a day.
In the accident report on the Cirrus above the pilot lasted nearly an hour at FL250/260. How would he have been at FL180/190?
Life is a risk and the only way to avoid that risk is to refuse to fly at levels where you need an oxygen supply. Any level over the universally accepted 10000 feet (Americans say higher) is a risk and mechanical things do break or go wrong.
Maybe any high level flights in non pressurised aircraft with oxygen should be avoided until more fail safe methods of supplying oxygen and monitoring the oxygen transfer are invented.
Otherwise we either take a risk or stay at home in bed.
Pace
Last edited by Pace; 1st Oct 2009 at 19:42.
It is possible to acclimatise to operating at high altitude without oxygen.
WW1 pilots operated regularly up to 22,000 feet in open-cockpit biplanes without oxygen, and often flew for up to 2 hours above 18,000 feet. They were very young and fit, though! Even so, it is clear from their accounts that it was physically punishing, especially in winter.
Mountaineers also are able to operate at altitudes in excess of 20,000 feet - Everest is 29,000 feet and has been scaled without oxygen.
The key is acclimatisation, in addition to cardiovascular fitness. Some people seem also to cope with / adapt better to reduced oxygen than others, even with apparently similar levels of fitness. Research is ongoing into possible genetic link to altitude capability.
FBW
WW1 pilots operated regularly up to 22,000 feet in open-cockpit biplanes without oxygen, and often flew for up to 2 hours above 18,000 feet. They were very young and fit, though! Even so, it is clear from their accounts that it was physically punishing, especially in winter.
Mountaineers also are able to operate at altitudes in excess of 20,000 feet - Everest is 29,000 feet and has been scaled without oxygen.
The key is acclimatisation, in addition to cardiovascular fitness. Some people seem also to cope with / adapt better to reduced oxygen than others, even with apparently similar levels of fitness. Research is ongoing into possible genetic link to altitude capability.
FBW
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Asked to climb to 11,000 feet to avoid a military exercise over the Florida panhandle, I complied.
My passenger was a teenage boy, heavy smoker (!) who had helped me to sail a small boat from Panama City Florida to St. Pete. I had tried before
to discourage his smoking with no effect.....
But when I informed him we would be climbing to an altitude where he might be more affected by a lack of oxygen than myself, and to let me know if his fingernails were turning blue, he spent the rest of the flight furtively examining his nails.....
often wondered if that experience helped him to kick the habit. Probably not.
My passenger was a teenage boy, heavy smoker (!) who had helped me to sail a small boat from Panama City Florida to St. Pete. I had tried before
to discourage his smoking with no effect.....
But when I informed him we would be climbing to an altitude where he might be more affected by a lack of oxygen than myself, and to let me know if his fingernails were turning blue, he spent the rest of the flight furtively examining his nails.....
often wondered if that experience helped him to kick the habit. Probably not.
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It is possible to acclimatise to operating at high altitude without oxygen.
The problem with planes is that even a slow one will reach FL200 in well under an hour. That is a helluva rate compared to climbing some place.
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Quote:
It is possible to acclimatise to operating at high altitude without oxygen.
You would have to do an awful lot of flying for that. Many thousands of hours a year, IMHO.
It is possible to acclimatise to operating at high altitude without oxygen.
You would have to do an awful lot of flying for that. Many thousands of hours a year, IMHO.
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A spiral dive will always take place pretty fast, in the absence of roll axis input. 1 hr is far too long.
I've gone for very long periods without any aileron or rudder input, without difficulty.
What occurred with this flight is not known. Guessing will not change that.
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What occurred with this flight is not known. Guessing will not change that.
