Hypoxia
Thread Starter
Join Date: Jun 2010
Location: Ottawa
Age: 64
Posts: 54
Likes: 0
Received 0 Likes
on
0 Posts
Hypoxia
The recent event of a TBM700 crew falling to hypoxia (apparently) raises a question. As both a former pilot and controller I am trying to look at this from both sides. The pilot had stated a need to descend from FL280 to 180 because of some erroneous indication but there was nothing alerting the controller that the issue was pressurization. If it was pressurization why not ask for FL100? Since the pilot did not declare an emergency I don't think you can argue that the controller should have moved heaven and earth to approve 180 as requested. He undoubtedly had conflicting traffic and after he cleared the initial descent to 250 then the pilot lost consciousness.
Having said that when dealing with the insidious nature of hypoxia (I remember the chamber all too well) the pilot's judgement is impaired. I think any issue to do with pressurization needs to be dealt with a little differently because the pilots faculties come into question. How should the system be changed to address this? I find it very paradoxical but would like to hear some thoughts.
Having said that when dealing with the insidious nature of hypoxia (I remember the chamber all too well) the pilot's judgement is impaired. I think any issue to do with pressurization needs to be dealt with a little differently because the pilots faculties come into question. How should the system be changed to address this? I find it very paradoxical but would like to hear some thoughts.
PPRuNe supporter
Join Date: Dec 2003
Location: Planet Earth
Posts: 1,677
Likes: 0
Received 0 Likes
on
0 Posts
This aircraft was the new TBM 900, one of the changes on this new airframe was an automatic pressurization system that is predicated on the destination city pair.
Join Date: Jun 2009
Location: Serenity
Posts: 20
Likes: 0
Received 0 Likes
on
0 Posts
What changes need to be made?
If the pilot feels there might be a pressurization issue, why not don O2 masks and then ask for clearance to descend?
If the pilot felt it was an emergency, why not descend to FL100 and then TELL ATC what's going on?
I'm not sure what happened to the other thread on this topic...but somebody summed it up nicely:
ATCs job is to separate traffic; not read the pilot's mind. The pilot's job is to fly the aircraft, and deal with issues as they arise.
If the pilot feels there might be a pressurization issue, why not don O2 masks and then ask for clearance to descend?
If the pilot felt it was an emergency, why not descend to FL100 and then TELL ATC what's going on?
I'm not sure what happened to the other thread on this topic...but somebody summed it up nicely:
ATCs job is to separate traffic; not read the pilot's mind. The pilot's job is to fly the aircraft, and deal with issues as they arise.
PPRuNe supporter
Join Date: Dec 2003
Location: Planet Earth
Posts: 1,677
Likes: 0
Received 0 Likes
on
0 Posts
Good points, but Taamguy brings out a something (I think) for controllers to possibly be a bit more curious about a situation where the pilot has some technical issue that requires a descent, because by the time the pilot recognizes some problem, he may already be seriously impaired by hypoxia.
Join Date: Jun 2009
Location: Serenity
Posts: 20
Likes: 0
Received 0 Likes
on
0 Posts
This seems like a very slippery slope. Can you have ATC question any request that doesn't make sense if it's requested from a pilot currently flying over FL100?
And ultimately, what can ATC do?
Even in this situation, ATC cleared the pilot down to FL200...the pilot acknowledged, yet never descended from 250.
We don't know what the "incorrect indication" was the pilot noticed...but it drove him to request a lower altitude...that tells me it was likely a correct-indication of a pressurization problem. Again...just like they tell the pax..."put on your own mask before helping others..."
And ultimately, what can ATC do?
Even in this situation, ATC cleared the pilot down to FL200...the pilot acknowledged, yet never descended from 250.
We don't know what the "incorrect indication" was the pilot noticed...but it drove him to request a lower altitude...that tells me it was likely a correct-indication of a pressurization problem. Again...just like they tell the pax..."put on your own mask before helping others..."
Join Date: Jun 2013
Location: Or-E-Gun, USA
Posts: 326
Likes: 0
Received 0 Likes
on
0 Posts
An Unfortunate Event
I think Taamguy and Dream Land both make excellent points.
In a potential crunch situation, Fly First. If, as this case suggests, a rapid descent to FL100 is necessary, start down, put the mask(s) on and then call ATC. Time is important. If a PAN or EMERGENCY call is even possibly warranted, skip the "Cool on the Radio" thing, make the declaration for God's sake, Tell ATC what problem is suspected. As once of these writer's notes, ATC's job is to provide separation - and they are darn good at it; they are not mind readers. I'd rather see a few a few more PAN/EMERGENCY calls that perhaps later get cancelled, than I would seeing accidents like this one, where we are still guessing about the cause - and the principals cannot tell us why they needed to descend. ATC's systems can and do identify/alert controllers to major variations in course or altitude and those folks are more than able to start getting others out of the way while they attempt to collect information. Sadly, we do not know what happened. Much of the speculation is probably close to the hard facts, but for some unknown reason, the pilots did not share much detail with ATC before they became unable to communicate. Assuming (admittedly a poor practice) that it was a pressurization issue and recognized by the pilot(s), instantly diving for FL100 and communicating in the way down does NOT violate any regulation that I've ever read. We may eventually know, but this airplane does not carry the same, high-end FDRs and CVRs standard on commercial transports, so even if the wreckage is located, it may not yield a lot of detail. For those lost, RIP; this loss **may** have been preventable. Sad.
In a potential crunch situation, Fly First. If, as this case suggests, a rapid descent to FL100 is necessary, start down, put the mask(s) on and then call ATC. Time is important. If a PAN or EMERGENCY call is even possibly warranted, skip the "Cool on the Radio" thing, make the declaration for God's sake, Tell ATC what problem is suspected. As once of these writer's notes, ATC's job is to provide separation - and they are darn good at it; they are not mind readers. I'd rather see a few a few more PAN/EMERGENCY calls that perhaps later get cancelled, than I would seeing accidents like this one, where we are still guessing about the cause - and the principals cannot tell us why they needed to descend. ATC's systems can and do identify/alert controllers to major variations in course or altitude and those folks are more than able to start getting others out of the way while they attempt to collect information. Sadly, we do not know what happened. Much of the speculation is probably close to the hard facts, but for some unknown reason, the pilots did not share much detail with ATC before they became unable to communicate. Assuming (admittedly a poor practice) that it was a pressurization issue and recognized by the pilot(s), instantly diving for FL100 and communicating in the way down does NOT violate any regulation that I've ever read. We may eventually know, but this airplane does not carry the same, high-end FDRs and CVRs standard on commercial transports, so even if the wreckage is located, it may not yield a lot of detail. For those lost, RIP; this loss **may** have been preventable. Sad.
Join Date: Oct 2009
Location: usa
Posts: 67
Likes: 0
Received 0 Likes
on
0 Posts
Start with a hypoxic pilot, that realizes that there is a problem, and in a semi-conscience state makes some close but no cigar decisions. He realizes he needs lower for oxygen, fixates on the number 10 thousand, and in his stupor does the math and comes up with 28 minus 10 equals 18 thousand, which he asked for, NOT the 10 thousand feet that he needed, with an immediate, emergency decent.
The aircraft was brand new. The ferry from France would indicate that the pressurization system worked.
A pinched seal would be insidious and could be undetected.
And if no one had checked if the crew O2 valve was turned on, well there you go.
The aircraft was brand new. The ferry from France would indicate that the pressurization system worked.
A pinched seal would be insidious and could be undetected.
And if no one had checked if the crew O2 valve was turned on, well there you go.
Join Date: Jan 2014
Location: glendale
Posts: 819
Likes: 0
Received 0 Likes
on
0 Posts
well meaning posts;
there is a difference between reading someone's mind and anticipation.
Thinking ahead. It is what makes flying and ATC possible.
Why would someone say words like: problem, and lower?
IF the engine quit, you would say: the engine quit, everyone remotely associated with our profession would understand that would mean you were going to descend (assuming everyone knows it is a single engine plane).
We went through this with aerolinas argentina and fuel. I'm sure some of you remember.
Radio work the world over needs improvement, in the meantime, just a reminder...remember apollo 13? I don't think Lovell said MAYDAY, he is quoted (generally) as saying: HOUSTON WE HAVE A PROBLEM. NOT houston we have an emergency.
PLEASE correct me if I am wrong about that.
there is a difference between reading someone's mind and anticipation.
Thinking ahead. It is what makes flying and ATC possible.
Why would someone say words like: problem, and lower?
IF the engine quit, you would say: the engine quit, everyone remotely associated with our profession would understand that would mean you were going to descend (assuming everyone knows it is a single engine plane).
We went through this with aerolinas argentina and fuel. I'm sure some of you remember.
Radio work the world over needs improvement, in the meantime, just a reminder...remember apollo 13? I don't think Lovell said MAYDAY, he is quoted (generally) as saying: HOUSTON WE HAVE A PROBLEM. NOT houston we have an emergency.
PLEASE correct me if I am wrong about that.
Pegase Driver
Join Date: May 1997
Location: Europe
Age: 73
Posts: 3,669
Likes: 0
Received 0 Likes
on
0 Posts
I fully support what has been said regarding controllers not being " mind readers"
We also teach our controllers that interpreting pilots voice intonations,or grammar used, and acting upon it , can be very dangerous. Of course after an accident and having a meeting with Captain Hindsight , the point : maybe the controller should have noticed ..etc.., always come back, and worse even on the courts . (for those old enough to remember Avianca B707 or the Yak42 in Tessaloniki to take only 2 cases ).
As it was said here and as I always preach ,please use PAN x3 , and you'll get everyone attention, and we can then all have a beer together at the bar discussing what I should have undertood or not.
We also teach our controllers that interpreting pilots voice intonations,or grammar used, and acting upon it , can be very dangerous. Of course after an accident and having a meeting with Captain Hindsight , the point : maybe the controller should have noticed ..etc.., always come back, and worse even on the courts . (for those old enough to remember Avianca B707 or the Yak42 in Tessaloniki to take only 2 cases ).
As it was said here and as I always preach ,please use PAN x3 , and you'll get everyone attention, and we can then all have a beer together at the bar discussing what I should have undertood or not.
Lovell didn't need to, the telemetry was screaming it at the top of its lungs. We don't have the benefit of telemetry so the pilot is the only means of obtaining information.
Join Date: Jan 2009
Location: Oxford, UK
Posts: 1,546
Likes: 0
Received 0 Likes
on
0 Posts
You will find the first comments on this sad accident on the North America forum, viewed by very few (only 29) under the title AIR FORCE TRACKING.
Perhaps the mods could combine the two threads, as some helpful ideas may evolve, particularly in the training of ATC to suspect possible hypoxia.
The pilot is usually the last person to recognise the problem.
Perhaps the mods could combine the two threads, as some helpful ideas may evolve, particularly in the training of ATC to suspect possible hypoxia.
The pilot is usually the last person to recognise the problem.
Join Date: Mar 2008
Location: Dublin
Posts: 415
Likes: 0
Received 0 Likes
on
0 Posts
I'm wondering whether it might be feasible to develop a system that causes a plane to automatically descend to something like 5000ft and squawk 7700 if there is no pilot input for a reasonable time period.
There are obviously some fairly major issues to be resolved before something like this could work in real life, but might that have prevented this incident?
There are obviously some fairly major issues to be resolved before something like this could work in real life, but might that have prevented this incident?
I think we're tackling this from the wrong end as it were.
When I did my commercial pilot training back in 1969 our course was taken to the nearby Royal Navy base where we did the hypoxia training - put in a chamber, taken to circa 40,000 feet pressure and given simple tasks to do having switched the oxygen off etc. This was done one at a time and it was an interesting experience to watch my colleagues' performance when subject to hypoxia.
It's an experience I have never forgotten and we were left in doubt about the dangers of hypoxia in flight.
In my opinion all those who fly pressurised aircraft should do hypoxia training and this would go a long way to avoid these sad incidents which happen from time to time.
Also it is essential to check oxygen systems for quantity, supply, correct fitting of mask prior to flight. At the slightest hint of a pressurisation problem oxygen masks should be donned.
Regarding descent with ATC a pressurisation failure is a MAYDAY as far as I am concerned. Also the whole idea of using the priority calls (MAYDAY or PAN, although the latter is not recognised in some states) is to draw immediate attention to one's plight. A vague request for descent on a busy ATC freq is never going to get the same attention as calling MAYDAY and/or wearing the 7700 badge if necessary.
When I did my commercial pilot training back in 1969 our course was taken to the nearby Royal Navy base where we did the hypoxia training - put in a chamber, taken to circa 40,000 feet pressure and given simple tasks to do having switched the oxygen off etc. This was done one at a time and it was an interesting experience to watch my colleagues' performance when subject to hypoxia.
It's an experience I have never forgotten and we were left in doubt about the dangers of hypoxia in flight.
In my opinion all those who fly pressurised aircraft should do hypoxia training and this would go a long way to avoid these sad incidents which happen from time to time.
Also it is essential to check oxygen systems for quantity, supply, correct fitting of mask prior to flight. At the slightest hint of a pressurisation problem oxygen masks should be donned.
Regarding descent with ATC a pressurisation failure is a MAYDAY as far as I am concerned. Also the whole idea of using the priority calls (MAYDAY or PAN, although the latter is not recognised in some states) is to draw immediate attention to one's plight. A vague request for descent on a busy ATC freq is never going to get the same attention as calling MAYDAY and/or wearing the 7700 badge if necessary.
I'm wondering whether it might be feasible to develop a system that causes a plane to automatically descend to something like 5000ft
FWIW I've "enjoyed"
similar training to that fireflybob describes - I agree entirely with his post.
Join Date: Apr 2003
Location: Germany
Age: 76
Posts: 1,561
Likes: 0
Received 0 Likes
on
0 Posts
Those guys headed for the Moon did not need any sort of ATC clearance, did they? I don't think you can find a strong parallel to this recent accident in their RT procedures.
ATC is not expected to have to guess at what a pilot needs to do and then sort out his problems for him. This is why we have to say, "Mayday, Mayday, Mayday" or at least in plain speech that magic word, "emergency." Saying that you need a lower altitude, well, yes, okay, but stand by for that; that could take a few minutes to work out on a routine basis.
You do get these tragedies where the crew had said, "We are low on fuel," or "We need priority," or whatever. Well, that's good to know, but if they were Number Six for approach, ATC was not going to jump them to the head of the queue just on the strength of that. You always have that question, asked or unasked by ATC, "What are your intentions?" That's you, the pilot-in-command, not some controller sat in a chair; he's already safely on the ground.
If this aircraft had a pressurization problem then the drill probably should have been something like: masks on; initiate emergency descent to FL100; declare emergency to ATC; squawk 7700; run emergency checklist.
That's all very well to sit here now writing about, but think of being sat there just enjoying the ride, your shiny-new turboprop humming along, when "BONG!" you have to start thinking, "Uh. What was that?" You could eat up a good minute or so just trying to figure out what your problem is, and then waste further time with this sort of "I need [this or that]," asking, when the controller is not going to drop everything to help you unless you declare an emergency and tell him what you are doing.
The TUC at FL280 is about three minutes or less. If this accident pilot were sat there, mask off at a pressure altitude of 28 thousand feet, then by the time the controller had sorted out the requested lower altitudes for him he might well have already been unable to respond effectively. It certainly looks as if that were the case.
ATC is not expected to have to guess at what a pilot needs to do and then sort out his problems for him. This is why we have to say, "Mayday, Mayday, Mayday" or at least in plain speech that magic word, "emergency." Saying that you need a lower altitude, well, yes, okay, but stand by for that; that could take a few minutes to work out on a routine basis.
You do get these tragedies where the crew had said, "We are low on fuel," or "We need priority," or whatever. Well, that's good to know, but if they were Number Six for approach, ATC was not going to jump them to the head of the queue just on the strength of that. You always have that question, asked or unasked by ATC, "What are your intentions?" That's you, the pilot-in-command, not some controller sat in a chair; he's already safely on the ground.
If this aircraft had a pressurization problem then the drill probably should have been something like: masks on; initiate emergency descent to FL100; declare emergency to ATC; squawk 7700; run emergency checklist.
That's all very well to sit here now writing about, but think of being sat there just enjoying the ride, your shiny-new turboprop humming along, when "BONG!" you have to start thinking, "Uh. What was that?" You could eat up a good minute or so just trying to figure out what your problem is, and then waste further time with this sort of "I need [this or that]," asking, when the controller is not going to drop everything to help you unless you declare an emergency and tell him what you are doing.
The TUC at FL280 is about three minutes or less. If this accident pilot were sat there, mask off at a pressure altitude of 28 thousand feet, then by the time the controller had sorted out the requested lower altitudes for him he might well have already been unable to respond effectively. It certainly looks as if that were the case.
Last edited by chuks; 8th Sep 2014 at 08:35.
There already is an automatic descend system fitted to the Cirrus (unpressurised turbocharged piston single). Details here:
http://cirrusengineering.b l o g s p...automatic.html
My understanding is that some bizjets are developing or implementing a similar system.
PS You need to manually fix the URL as PPRuNe doesn't like blog spot for some reason
http://cirrusengineering.b l o g s p...automatic.html
My understanding is that some bizjets are developing or implementing a similar system.
PS You need to manually fix the URL as PPRuNe doesn't like blog spot for some reason