Flying High Unpressurized (2016) | Hacker News Reader

Flying High Unpressurized (2016)

planeandpilotmag.com

52 pointsHooke34 comments

A hard drive crash once caught me off guard at high altitude.

Admittedly less of a concern these days, but back in the era of spinning disks I thought it would be fun to take my netbook up loaded with approach plates.

Turns out yes, the read write head is supported by a thin cushion of air. As the air becomes less dense so does the cushion until - yup you guessed it - head crash.

It’s well documented now of course but I understand it also used to be a problem in Tibet and Chile.

Great article, both informative and detailed.

One thing I would add is that most sea-level habituated people are measurably hypoxic over 5,000 feet or so. It's just not as obvious.

If you're a pilot, there's an interesting self-test you can do on yourself the next time you fly VFR at night. At about 8 or 9,000MSL, without oxygen, take a look at the landscape below. Looks normal, right? Now breathe some oxygen while continuing to look.

For most people, it's like having the contrast turned way down on a TV and not realizing it. Once the contrast comes back up, there's all this depth of color, vibrance and detail you had been missing -- and have not been aware of it.

If you're like me, the crazy part isn't that you were hypoxic. It's that everything seems completely normal. You can't use an out-of-whack system (your brain) to judge whether it's out-of-whack or not.

My impression is that cabin altitude on a pressurized airliner might be up to 8,000 ft.

Destin at Smarter Every Day shows you the effects of hypoxia and why you should put your mask on first before helping a child or other passenger.

https://www.youtube.com/watch?v=kUfF2MTnqAw

My wife still remarks that she'll put on our daughter's first, and I'm like please, please, please don't do that, there's a reason they say this. If you pass out, you can't help anyone else. It doesn't seem to get through to her.

https://youtu.be/kUfF2MTnqAw?t=395

I was just flying today and noticed times printed on the safety card. I recall it had getting your own mask secured in 5-7 seconds and getting to assisting children by 10 seconds.

It's the first time I recall seeing times printed and it really illustrates how quickly it'll hit the fan. 10 seconds isn't alot of time but the order is still critical.

I wonder if that clarity on timing would frame it better for other people instead of an open ended 'me before them' blanket rule.

Reminded me of the two times I’ve been hypoxic. One was in the altitude chamber. The Navy was great about training and had all pilots experience hypoxia so they could understand how the symptoms effect them in particular. My first indications was tingling fingers. The second time was flying into Iraq. I had skimped on the preflight checklist and missed the cabin pressure switch, which was always in the on position, but had somehow been set to off. Took my mask off at 20k heading in country and started to feel light headed with tingling fingers. Told my commanding officer / flight lead something was wrong. We started to return to the carrier. During the emergency procedure checklist hit the step to check the cabin pressure switch. Oops. “Sir, we don’t have to abort the mission!” The Navy had some great training that saved my life on more than one occasion.

I was in a Cessna 206 headed to Oshkosh. Our pilot had planned to fly Eastbound at 17,000ft to avoid an air current. We all got nasal cannulae for supplemental oxygen. We departed at 3AM, and following takeoff I immediately fell asleep.

I woke up somewhere around 14,000ft, dizzy and confused, and realized I hadn't put my cannula in before falling asleep. I fixed this, and within a minute the brain fog was gone and I proceeded back to sleep.

Then we hit turbulence, which in a small craft like a 206 means you occasionally whack your head on the ceiling. Couldn't sleep through that.

The author mentions that he would design a system with a continuously monitored pulse oximeter that could trigger the EPS descent mode automatically. Do wrist-mounted versions (fingertip ones would probably be too bulky/uncomfortable for continuous use by someone at the controls) of such continuous oximeters exist at the moment? The Apple Watch apparently has a sensor capable of measuring blood oxygen content, but disabled that functionality for unstated reasons (FDA regs?) [1], and I'm unaware of any extant wrist-worn device with that functionality enabled.

[1] https://9to5mac.com/2015/04/24/apple-watch-blood-oxygen/

Some more information about the physiology of hypoxia can be found here: https://web.archive.org/web/20150318011408/dr-amy.com/rich/o...

Autopilot descent triggered by hypoxia alarm has been available for quite a while. It uses responsiveness heuristics rather than oximeter input.

https://www.aviationpros.com/press_release/10393999/cirrus-a...

The Garmin Fenix has a pulse oximeter.

https://www8.garmin.com/manuals/webhelp/fenix5plus/EN-US/GUI...

Unpressurized high performance single engines are basically the number one private pilot killer. Dentists and business men with a few hundred IFR hours will go up solo in their new million dollar TBM, lose oxygen, descend into icing, and that's a wrap. Don't be one of those guys.

A TBM is pressurized. Article is about unpressurised planes. TBMs also have quick-don masks as standard equipment and very loud alarms warning you if cabin depressurizes

>A TBM is pressurized. Article is about unpressurised planes. TBMs also have quick-don masks as standard equipment and very loud alarms warning you if cabin depressurizes

The problem is they lose pressure all the time. And when that happens, the average pilot has no ability to figure out what's happening or fix the problem until it's too late. They market these planes to people that really shouldn't be flying them, no different than high end sports cars.

Checklist for depressurization alarm says to put on quick-don mask. That is all you need to do to prevent a fatal outcome, after that, you have plenty of time to diagnose the issue or safely descend. Not sure what you are talking about, but a pilot unable to execute the first item on a checklist has other problems clearly.

You have very little time to correctly don a mask. It’s a serious situation with a high risk of death.

Nonsense!

TUC at 30,000 feet is 1 to 2 minutes if slow decompression, 30-60 seconds if rapid. If you lack cöordination and movement ability to reach two feet, grab a mask and apply it to your face in that time, you have no business flying a plane (or for that matter doing anything else like driving or operating a basic dinner cutlery set like a fork and a knife)

Rapid depreciation is a highly stressful situation. You need reolize the single most import thing to do not ‘just fly the plane’ or check the dammage, but rather to start putting on a mask in a few seconds or you will die. Waiting wasting even 20 seconds may not give you enough time to finish putting the mask on properly.

The US Air Force has a long list of people who failed to do the correct thing in similar situations. On top of that even assume you would get it right 99/100 times that’s still more danger than most people experience over a full year.

USAF flies a lot higher than 30k. most single engine turboprops do not. HUGE difference. TUC at 40k is seconds...

USAF stretches back through a long history of aviation. They really have lost people at 30k feet to this.

It makes me think of jumping out of a plane. Pulling the cord to open your parachute sounds like a really simple thing, but doing a really simple thing correctly and quickly when you are otherwise about to die is harder than you might think. And when skydiving, even for the first time, you get to prepare for the event, rather than having it sprung on you.

This is precisely why people train for sudden depressurization. That way when the unexpected thing happens, you're ready for it anyways. If you're not, nobody should have given you your license. I know friends who have had real emergencies and handled them gracefully. I have had my engine suddenly quit on me while I was over downtown Dallas, and I've had my oxygen system fail up in the flight levels. Handled both just fine. If you were well-trained, training just kicks in.

If something bad going suddenly scares you, if you're not comfortable with your ability to handle sudden spikes in stress, you're just not cut out to be a pilot.

Something clicked when you mentioned being ‘given a license.’

Realistic and regular training can make a huge difference and is really important. But, it only goes so far. Some people simply react poorly in stressful situations so organizations tend to simply resort to filtering people out. That does not happen nearly as much in general aviation.

Sometimes people go unaturally calm, other times they flip out and it’s not always predictable how someone is going to react. So, this might not be an issue for you, but plenty of evidence suggests it is a widespread issue.

"If something bad going suddenly scares you, if you're not comfortable with your ability to handle sudden spikes in stress, you're just not cut out to be a pilot."

Perhaps, but if you think it is possible to be certain of your ability to handle stress before actually experiencing it, then you have never been tested.

...are there stats on that? It's my impression that poor pre-departure decision making - especially regarding WX and w & b - are the very, very simple things which tend to kill private pilots.

Arguably, taking off along a route where one could potentially be stuck in icing for an extended period, in an aircraft not capable of that, is the definition of poor pre-departure decision making. Commercial airliners have relief to dispatch with malfunctioning anti-ice gear. The procedures almost always dictate that flight in known or forecast icing conditions is prohibited. Basically, if it’s not summer and there’s a cloud in the sky you’re not going. Icing is not something to mess around with in an aircraft not properly equipped for it.

Can someone explain this in layman's terms? This is interesting to me but I've lost the meaning in the jargon. TBM? "Descend into icing"? IFR hours?

TBM-a brand of single engine turboprop airplane.

Descend into icing-you don’t pickup ice in clear air. You don’t pickup ice below about -20C generally. You can be in a situation where you climbed through an icing or possible icing layer and above it are not in danger of picking up ice. If you have to descend back into it and linger, you may need to.

IFR hours-Instrument Flight Rules; controlling and navigating without visual references.

Uh, no, not even close.

Latest Nall Report [1]: 73.8% due to pilot-related (action or inaction).

A TBM is pressurized, and would "lose oxygen" only if the cabin had already depressurized, either due to a rare malfunction (like the TBM 930 a year or two ago) or a pilot not knowing how to work the pressurization controller and climbing up into hypoxic altitudes, and then ALSO not having his emergency oxygen supply stocked, or not attempting to use it at all.

I'm surprised at your comment, to be honest, and the only motive for it I can guess is envy. Dentists and Businessmen in million dollar planes are a thin thin sliver of the General Aviation population.

[1] https://www.aopa.org/-/media/files/aopa/home/training-and-sa...

I think you're misinterpreting hangar talk for aviation safety advice. The "dentist crashing his expensive plane" has been a trope in the aviation community for a long, long time. (Perhaps at some point it matched up with the stats? I don't know) By now, it's apocryphal, the point being that focusing on the gear or the money involved instead of actually managing risk is a good way to get killed.

I used to read the safety stats a lot. One of my favorites was "running out of gas". It always amazed me how many really good pilots and really good airplanes ended up in a bad way because of simply running out of gas.

Its extremely hard to detect hypoxia in yourself. Since your own detection apparatus is faulty it usually doesn't work. Your best bet is to see if anyone else looks like they have hypoxia, and if so should trigger the thought that you might as well. Think of it like being able to tell if you are in a dream, it takes most people some practice to tell, even though it seems like it should be simple

that audio for Cirrus, N591WA ... oooohhhh.... mmmyyyy ....

https://www.faa.gov/data_research/accident_incident/2011-05-...

If you’re going to do this, spend $30 and get a can of BOOST oxygen and a pulse oximeter with an alarm.

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