Hypoxia

[Dream Land]

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.

Wow, brilliant idea old chap, why didn't all of us pilots think of that!

Hopefully there will be some more positive input on this thread, since alarms and training seem to be falling short in several unfortunate instances.

[TAAMGuy]

Hypoxia Paradox

The recent incident, apparently, involving hypoxia has raised a point about the ATC involvement. As both a former pilot and controller I am trying to look at this from both sides. Prior to being rendered unresponsive, the pilot requested descent from FL280 to FL180. He accepted an interim descent to FL250 but reiterated he needed lower. The controller responded "I'm working on that'; meaning (I assume) he had conflicting traffic. The pilot stated he had some sort of indication in the cockpit but never said it was related to pressurization, and never declared an emergency.

What I am wondering about is in a situation where a controller is informed that pressurization is potentially compromised, should the controller not 'force' the aircraft down, because the pilots judgement is now called into question?

We as controllers certainly do not want to be in the business of flying the aircraft on your behalf, but since hypoxia is often insidious, at what point do we save you from yourself? Is this an additional layer of safety that the pilot community would want to be added?

Obviously this is a very sensitive issue, but i would love to generate some constructive discussion.

[roninmission]

Technically it would be relatively simple for pilots to wear a blood oxygen level meter which could give a wireless warning either to the pilot or some other device which would alert ATC

[Dream Land]

Pilots wouldn't need to wear something like that, but a transducer could easily give ATC the cabin altitude if it becomes dangerous. I'm not asking for controllers to be mind readers, but there has to be a way to make things safer.

I was also trained in the high altitude chamber, but it doesn't make me anymore resistant to the effects of hypoxia, it was only a demonstration.

[stilton]

In a depressurization situation, especially a rapid one you don't wait for permission from a controller.


You put your mask on and start down. When you have time, after completing your immediate action items you TELL them you are descending and declaring an emergency.


Obviously you have to be aware of traffic beneath you and monitor your TCAS but I wouldn't be waiting on ATC, there's just no time as this pilot found out the hard way.

[Dream Land]

Yes Stilton, I think most people sitting in a class room can figure that out, what I think some are discussing here is how the effects of hypoxia has interfered with that plan.

Take a look at just some of the accidents, LJ, 737, Cirrus, TBM, there's probably more.

It's very easy in the simulator because they tell you by making a big bang sound, not always that simple in real life.

[fireflybob]

Yes Stilton, I think most people sitting in a class room can figure that out, what I think some are discussing here is how the effects of hypoxia has interfered with that plan.

Take a look at just some of the accidents, LJ, 737, Cirrus, TBM, there's probably more.

It's very easy in the simulator because they tell you by making a big bang sound, not always that simple in real life.

Not always! As an instructor on the simulator I often used the slow loss of pressure as this was a much more likely scenario and brought out some salient points.

No disrespect to private owners but how often do they practice the loss of press/emergency descent drill?

Within the airline world there is a requirement to do this on a regular basis and also the drills are often covered during line checks too.

This is mainly a matter of discipline and training.

What stilton says is correct and this is what should be taught and practised.

[Dream Land]

Practicing the "High Dive" is one of the items practiced in training for most TBM owners, some in the simulator, some train in their own aircraft. Again, pointing out the obvious is not doing a lot to help the problem here, all pilots are taught this maneuver.

Somehow getting an earlier notice needs to happen.

[BOAC]

Does the a/c have any cabin altitude warning?

[TAAMGuy]

As a controller, if I was informed that there was a pressurization issue, and a descent request, i would consider that as good as a declaration of emergency. However, just the fact that the pilot has told me he has a pressurization issue, I'm going to really be paying attention to his voice in an effort to assess how he is being affected. If i hear the voice wavering, i would inclined to force the aircraft down. I would also be more wary of a GA pilot than airline.

Should there be an SOP introduced for both parties that mandates a descent in the event an issue with pressurization has been identified? Whether or not the pilot requests it? Morally, at what point do I believe the pilots judgement has been compromised and take action?

[4Greens]

Agree entirely with the respondents who say immediate 'Mayday'. Apart from ATC it warns all other aircraft on the frequency.

Nuff said.

[glendalegoon]

dear atcwatcher

I actually do know quite a bit about ATC, Radio phraseology and more. I've been making my living as a pilot for 35 years or more. By the way, we don't say R/T here in the USA. Its just radio. Ask a fellow named Lee DeForest.

BUT I do know that many pilots are imprecise in their use of radio. And ATC has adjusted to non standard phraseology. Indeed, I've heard ATC use some non standard phraseology now and again. I realize that in europe, everything is perfect.

Those who wonder why the pilot didn't request 10,000'? Well, he may have been impaired. He may have seen the cabin differential would hold a cabin altitude of 8000' at FL180. He may have been trying to salvage things instead of declaring an emergency. Pilots are like that. Declare an emergency and most likely things are going to heck in a handbasket quickly and may (subconsciously) signal defeat.

While many can read the controller/pilot glossary, it takes someone who has been around awhile to read a situation.

Does anyone know how long the controller had been checked out at Center? Was he a journeyman of many years or a newly checked out controller?

Taamguy makes a good point.

[Tarq57]

Originally Posted by TAAMGuy

As a controller, if I was informed that there was a pressurization issue, and a descent request, i would consider that as good as a declaration of emergency. However, just the fact that the pilot has told me he has a pressurization issue, I'm going to really be paying attention to his voice in an effort to assess how he is being affected. If i hear the voice wavering, i would inclined to force the aircraft down. I would also be more wary of a GA pilot than airline.

That's how I'd treat it, too. I think that's how most controllers - particularly experienced controllers - would treat it.

Should there be an SOP introduced for both parties that mandates a descent in the event an issue with pressurization has been identified? Whether or not the pilot requests it? Morally, at what point do I believe the pilots judgement has been compromised and take action?

Tricky. Unless such info (cabin pressure) is datalinked to ATC, or is displayed as part of a mode "s" readout on the datablock, or the pilot actually informs ATC there's a pressure issue (say, prior to to becoming incapacitated) you're just groping around in the dark. And with probably little or no reason to suspect anything is wrong.
If the pilot mentions it but sounds vague the effect is probably already happening, and strongly encouraging a descent/reminding them to put the mast on might work, or it might already be too late.
I don't think a telepathy rating can be mandated via a SOP, but it's a nice idea.

[TAAMGuy]

I think that Mode S could definitely be exploited for this purpose. A message could easily be sent as part of regularly broadcast telemetry that would present on the controller's display that the pressurization system has been compromised. If after being queried, the crew does not confirm they are using supplementary O2, then the controller forces the flight down to FL130, or at least an altitude low enough to bring the pilots back some of their brain function. Obviously factors such as MEA, MAA, and MRA need to be considered. (Terrain)

I know that there is a culture prevalent among pilots that does not embrace the idea of transmitting data about the aircraft beyond what is currently available, but honestly it is about CDM. System Wide Information Management (SWIM) or Cloud, is being embraced by ANSP's, airlines, and others as the way of the future. The more data a controller has access to about a flight, the better the SA. My two cents worth.

[Una Due Tfc]

If the cabin altitude warning goes off, the aircraft should be descending without clearance, and when the crew has time, squawking 7700. The squawk is much more important than the Mayday transmission as all effected sectors will see it.

If there needs to be a Mode S feed from the cabin altitude sensor to my display so that I can tell a crew to do something that realistically they should already be doing, then I despair for this industry

[Tarq57]

Just for anyone not in the industry reading this thread, there is no way a controller can force an aircraft to descend.

We can instruct or clear, even urge. Only the flight crew (or fuel exhaustion) can "force" the flight to descend.

[BOAC]

Does the a/c have any cabin altitude warning? (Again!)

[glendalegoon]

dear boac

I read on another thread that a warning happens at 10,500' cabin altitude and it is displayed on one of the electronic displays.

I've not flown this type but am guessing its not a big horn like on a 737 or something.

I think the other thread is on pprune under the title: air force tracking...

good luck.

[BOAC]

Ta, Glen - found it in North America.