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[ARCHIVED THREAD] - Non-pressurized at FL280?

Posted: 7/15/2016 12:20:04 PM EDT

I'm entertaining the idea of purchasing another airplane (aren't we all?). My short list includes some turbo non-pressurized aircraft, a couple of them are certified to 28,000 ft. I've taken my NA Mooney up to 17,000 ft and it felt a bit hairy up there. I was using a cannula when I should've probably been using a mask. What's it like being unpressurized at 28,000 ft? Can it be at all comfortable? There are two things that I've heard that sound contradictory: one is that you can lose consciousness in seconds at that altitude, the other is that when you're on pure oxygen you can be more saturated than you are at sea level and go for a while if something goes wrong.

Posted: 7/15/2016 12:48:57 PM EDT

[#1]

probably pretty damn cold

Seems pretty dang high for non pressurized (small GA)? 28000 as critical altitude is uncommon isn't it? isn't around 20k more the usual?

sorry, more questions than answers

Posted: 7/15/2016 1:33:12 PM EDT

[#2]

You need to get high altitude training and a session in an altitude chamber.

You can get dead real quick screwing around at high altitude without the training and the proper equipment.

From personal experience I can tell you that rapid decompression at 45,000' will make the previous evening's nachos trumpet like a train horn.

Posted: 7/15/2016 1:35:01 PM EDT

[#3]

I've lost pressurization at that altitude a couple of times, when I was in the Navy. In fact, I flew across the North Atlantic that way. No problems at all, since we were on oxygen all the time, anyway.

I wouldn't recommend it though. Take off the mask at that altitude, and it's good night Irene.

Posted: 7/15/2016 2:25:21 PM EDT

[#4]

Time of Useful Consciousness is what you want to know about. at FL28 you have about 2-3 mins... Depending on a bunch of factors.
But the issue is that the as soon as you lose O2, your judgement goes to crap.

Posted: 7/15/2016 3:12:02 PM EDT

[#5]

Dress for success at FL280

Posted: 7/15/2016 7:47:31 PM EDT

[#6]

Quote History

Quoted:
You need to get high altitude training and a session in an altitude chamber.

You can get dead real quick screwing around at high altitude without the training and the proper equipment.

From personal experience I can tell you that rapid decompression at 45,000' will make the previous evening's nachos trumpet like a train horn.

View Quote

It wasn't in a G3, was it? I know at 17,000 I was freezing, granted, it was 20F degrees outside on the ground; lapse rate I guess would put it at around -40F. The metal trim wheel and controls felt like frozen metal with frost. I was making 175kts over the ground at an IAS of only around 105kts though.

Posted: 7/15/2016 9:39:41 PM EDT

[#7]

I've flown helicopters above fl200 with a mask on a demand regulator, but always with 2 pilots on independent oxygen systems and an entire spare oxygen system from bottle to mask. If the temps are reasonable or you have a good heater it's not bad.

I'm too old to do that without a good reason and I can't come up with any compelling reason to do it alone on a regular basis. Once in a blue moon to get a 100kt tailwind maybe, but that's even a stretch.

Posted: 7/16/2016 1:27:20 PM EDT

[#8]

Posted: 7/16/2016 2:36:06 PM EDT

[#9]

We took my B36TC up to FL 23 on a flight from Chicago to Dallas. Canula. Cold ( we were in shorts). Cows are really small at that altitude. Fun flight. Started our decent a LONG ways out.

Posted: 7/16/2016 4:02:40 PM EDT

[#10]

As part of flight testing for our Chelton AP-3C a/p, we took a T182 up to 28k. It took a really long time to get there.

Posted: 7/16/2016 6:40:17 PM EDT

[#11]

Some buddies and I spent an afternoon climbing a normally aspirated 182 to 16,500 and some change 20 years back just for giggles. I think it would have slowly gone higher but we were already bored of it and that whole class A airspace thing. That's as high as I've ever flown a normally aspirated or unpressurized plane.

Posted: 7/16/2016 7:30:44 PM EDT

[#12]

Quote History

Quoted:

Some buddies and I spent an afternoon climbing a normally aspirated 182 to 16,500 and some change 20 years back just for giggles. I think it would have slowly gone higher but we were already bored of it and that whole class A airspace thing. That's as high as I've ever flown a normally aspirated or unpressurized plane.

View Quote

I've had a Husky up to 17,500. I almost filed an IFR to see if it would have made it to the 20,000 service ceiling.

Posted: 7/18/2016 11:25:58 PM EDT

[#13]

What models you looking at? Had my 201 up to 17k once. Turbo pistons can run hot at altitude. Thin air less heat loss.
Intercooler mandatory I think.

Posted: 7/19/2016 12:01:50 AM EDT

[#14]

I wouldn't mess with it. The gains are minimal unless you just enjoy pushing the limits of old technology. I would also never do it without a second pilot on a separate system.

ElSupremo is spot on, as usual regarding the chamber... That is a must if you want to play that game. Hypoxia really effects everybody differently. I've seen fit military guys with a time of useful consciousness far less than the "average" of 2min. It isn't something that is necessarily predictable or always repeatable.

Posted: 7/19/2016 12:04:51 AM EDT

[#15]

Wear a jacket.

Posted: 7/21/2016 1:29:02 AM EDT

[#16]

Time of Useful Consciousness gets short, and a lot of people have hypoxia onset symptoms that are hard to differentiate from either a stress response or abnormal environmental conditions. Get a chamber flight. They are educational!
Unless you are trying to get above poor weather, I don't see the point.

Posted: 7/22/2016 1:25:28 PM EDT

[#17]

Flew a T-37 Tweet (unpressurized) at FL250. Of course, we wore O2 masks the whole time every flight. I was farting a lot up at 250, too. Thank goodness for the masks.

Posted: 7/22/2016 10:13:43 PM EDT

[#18]

I got a Piper J4 up to 16,500 once. There wasn't a whole lot of performance between climbing and descending. Had a flight of F4's pass a couple hundred feet under me.. I felt like a target, I couldn't go up, down, left, or right fast enough to get away. I don't think they ever saw me.

Posted: 7/23/2016 6:40:51 PM EDT

[#19]

I once flew a 1946 Taylorcraft over Tulsa at 12500 feet. A long time ago.

[ARCHIVED THREAD] - Non-pressurized at FL280?

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