High altitude flight (relatively speaking)

[A64Pilot]

16 hours ago, M20F said:

Should have kept the F they do 250 with no issues. 
 

 

Heck, I did that with a Crop Duster and still was climbing in excess of 1,000 FPM

 

[M20F]

3 hours ago, A64Pilot said:

Heck, I did that with a Crop Duster and still was climbing in excess of 1,000 FPM

 

PT6 is a hell of a thing. 

[A64Pilot]

42 minutes ago, M20F said:

PT6 is a hell of a thing. 

-67F at 1700 SHP is a hell of a thing  

[Huckster79]

On 7/17/2023 at 12:40 AM, EricJ said:

Another thing that helps is taking consistent deep breaths.    It's hard to remember to keep it up, but it can make a big difference.    I've seen my saturation levels go up significantly just by doing that.

Absolutely!  I once flew my Cessna 140 from Michigan to Johnson creek Idaho.  I’d been at 9500 or so most of the day.  All the sudden found myself having extreme difficulty calculating out where I should adjust my next stop to, as headwinds were larger than predicted.  It was right after feeling euphoric I was out west again.  I’d figured the euphoria was just excitement of being out there.  Then when I couldn’t hardly calculate which airport I should go to- I realized something was wrong and decided to land at next airport. 
 

on the way there I noticed how shallow I’d been breathing.  Focused on that, landed, had lunch and proceeded just fine but focused on my breathing.  I’m convinced my shallow breathing had likely lowered my saturation.  Prob was excitement and nerves of a flat lander knowing he’s not above the flat bread basket anymore.   Turned out fine but demonstrates what you’re saying! 
 

now that I got the Mooney I want to get O2 can for any long flight 8 or more… can’t hurt.  

[Rick Junkin]

On 7/17/2023 at 12:57 AM, ilovecornfields said:

I wrote a letter to the editor recently to one of the big flying magazines who published an article about hypoxia and didn’t even mention just buying a pulse ox and using it. Crazy.

Here's the one I use. I wear it on the pinky finger of my left hand. I've crosschecked it with my Masimo MightySat and it's always within 2%. I like the Wellue ring because it's always on my finger and has an adjustable vibrating alarm. Plus I can download a flight's data to my iPhone for a quick check to see if I had any indications my O2 system isn't 100% or perhaps my breathing pattern needs some work. 

Cheers,
Rick

https://www.amazon.com/Wellue-Monitor-Continuously-Tracking-Software/dp/B08VW3VQKW/ref=sxin_16_pa_sp_search_thematic_sspa?content-id=amzn1.sym.4a292f39-c27c-4e62-9abd-d68116d07607%3Aamzn1.sym.4a292f39-c27c-4e62-9abd-d68116d07607&cv_ct_cx=health+ring+tracker&keywords=health+ring+tracker&pd_rd_i=B08VW3VQKW&pd_rd_r=58eea802-06b1-429d-abb9-c58e86eb84cc&pd_rd_w=NZ8Tf&pd_rd_wg=7dU7t&pf_rd_p=4a292f39-c27c-4e62-9abd-d68116d07607&pf_rd_r=HD9CZ5E25C7S8T3C3KXA&qid=1689707749&sbo=RZvfv%2F%2FHxDF%2BO5021pAnSA%3D%3D&sr=1-1-2b34d040-5c83-4b7f-ba01-15975dfb8828-spons&ufe=app_do%3Aamzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840&sp_csd=d2lkZ2V0TmFtZT1zcF9zZWFyY2hfdGhlbWF0aWM&psc=1

 

[Fly Boomer]

1 minute ago, Rick Junkin said:

Here's the one I use. I wear it on the pinky finger of my left hand. I've crosschecked it with my Masimo MightySat and it's always within 2%. I like the Wellue ring because it's always on my finger and has an adjustable vibrating alarm. Plus I can download a flight's data to my iPhone for a quick check to see if I had any indications my O2 system isn't 100% or perhaps my breathing pattern needs some work. 

I have looked at something from Wellue in the past, and you can get something wearable that's not clumsy, but I also wanted a way to get an alarm into my headset, and I don't remember that being available -- I'm just not likely to look at my phone every few seconds to make sure I'm still okay.  Does yours do it?

[Rick Junkin]

20 minutes ago, Fly Boomer said:

I also wanted a way to get an alarm into my headset

No, the Wellue ring I have only has a vibrating alarm, but it's very effective and the vibration intensity is adjustable, as well as the O2 level at which it triggers. It has an integrated display that alternates between O2 sat and pulse rate.

You might want to look at the offerings from Aithre

https://aithreaviation.com

EDIT: Yeah disregard. Aithre has a very nice system but it doesn't have headset aural alerts. My bad.

Cheers,
Rick

[Fly Boomer]

53 minutes ago, Rick Junkin said:

No, the Wellue ring I have only has a vibrating alarm, but it's very effective and the vibration intensity is adjustable, as well as the O2 level at which it triggers. It has an integrated display that alternates between O2 sat and pulse rate.

You might want to look at the offerings from Aithre

https://aithreaviation.com

EDIT: Yeah disregard. Aithre has a very nice system but it doesn't have headset aural alerts. My bad.

Cheers,
Rick

Thanks for that link.

[Fly Boomer]

1 hour ago, Rick Junkin said:

Here's the one I use. I wear it on the pinky finger of my left hand.

Does that ring fit okay on your pinky finger?

[Rick Junkin]

20 minutes ago, Fly Boomer said:

Does that ring fit okay on your pinky finger?

Yes, fits fine. I have a size 11 ring finger, for reference. I tried it on my thumb as recommended by Wellue but it is way too small for my thumb.

[wombat]

I'm relatively healthy (crossfit 3X to 5X a week, plus cardio workouts) and relatively young (less than 50), have never smoked, and I've always scored very well on anything physical or health related.   So I figured I was fine right at the FAA limits on Oxygen.     Don't have O2 with me?   Just cruise at 12,500 for hours!   It's fine to bump up to 14,000 for 30 minutes!

Turns out that no, this is one way that my body lets me down.   If I'm at 13,500 for 20 minutes, my O2 is in the lower 70's as measured by my pulse oximeter.     I get really sleepy and really dumb. (Oddly enough the pulse oximeter I have is exactly the one pictured in this article: https://www.news-medical.net/health/What-is-Oxygen-Saturation.aspx)

So now that I have built-in oxygen, life is way better.    I like the concept of a O2 sensor that is attached to me so I don't have to remember to put it on every few minutes, and it has an alarm.  That will make me a lot more comfortable at the lower flight levels (up to about FL230).

Edited July 18, 2023 by wombat

[Fly Boomer]

2 hours ago, wombat said:

That will make me a lot more comfortable at the lower flight levels (up to about FL230).

"Lower flight levels" for the Rocket.

[ilovecornfields]

15 hours ago, wombat said:

I'm relatively healthy (crossfit 3X to 5X a week, plus cardio workouts) and relatively young (less than 50), have never smoked, and I've always scored very well on anything physical or health related.   So I figured I was fine right at the FAA limits on Oxygen.     Don't have O2 with me?   Just cruise at 12,500 for hours!   It's fine to bump up to 14,000 for 30 minutes!

Turns out that no, this is one way that my body lets me down.   If I'm at 13,500 for 20 minutes, my O2 is in the lower 70's as measured by my pulse oximeter.     I get really sleepy and really dumb. (Oddly enough the pulse oximeter I have is exactly the one pictured in this article: https://www.news-medical.net/health/What-is-Oxygen-Saturation.aspx)

So now that I have built-in oxygen, life is way better.    I like the concept of a O2 sensor that is attached to me so I don't have to remember to put it on every few minutes, and it has an alarm.  That will make me a lot more comfortable at the lower flight levels (up to about FL230).

I think your experience is pretty typical and representative of the FAA’s dated guidance on the subject. Most CFIs at the pilot mill schools don’t seem to do a lot of XC trips (since they can’t afford it) so they do a poor job teaching about real-world hypoxia and oxygen use in primary training. 

I get the feeling a lot of the “get there itis” and “poor inflight decision making” incidents had hypoxia as a huge contributing factor. There are a lot of hypoxic pilots flying around out there thinking that because they’re under 12,500 they are fine (even when the density altitude is 14.5k+).

Given how cheap a pulse ox is and the increasing number of people with chronic lung diseases over the last couple of years it seems it’s time for the FAA to at least issue an AC with more realistic and helpful guidelines.

[tgardnerh]

 
I get the feeling a lot of the “get there itis” and “poor inflight decision making” incidents had hypoxia as a huge contributing factor.

I'm convinced that a huge portion of the danger of mountain flying is just that we get varying degrees stupid when hypoxic. So many accidents seem to be a variation on "after cruising at 11,500 feet for an hour, pilot who definitely knows better continued flight into weather/rising terrain/improper landing site."


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[Pinecone]

A friend lost an RV-7 and partner.  I helped clean out the hangar (multi plane) and we found the portable O2 rig and the Sentry ADSB.

Partner flew the plane into a thunderstorm.  After some time at 15,000.  Hmmmmm

I wonder if a bit of hypoxia impaired ADM.

[gabez]

interesting topic. I did some testing on myself while flying my 231. Basically, for myself, at 11-12.5 I am sitting at about 86% O2 and goes downhill from there 

[aviatoreb]

On 7/18/2023 at 4:55 PM, Rick Junkin said:

Yes, fits fine. I have a size 11 ring finger, for reference. I tried it on my thumb as recommended by Wellue but it is way too small for my thumb.

I have the exact model - its fantastic - especially because it is doing continuous O2Sat monitoring and vibrates when you are too low - like low 90s is it?

[aviatoreb]

On 7/19/2023 at 10:55 AM, ilovecornfields said:

... thinking that because they’re under 12,500 they are fine (even when the density altitude is 14.5k+).

Is that how it works?  I know it is density altitude that counts for think about air foils and engine performance - but is it the same for the wetware?  Is it density altitude that controls the quality of my biological (brain!) function?
E

[Hank]

4 minutes ago, aviatoreb said:

Is that how it works?  I know it is density altitude that counts for think about air foils and engine performance - but is it the same for the wetware?  Is it density altitude that controls the quality of my biological (brain!) function?
E

Unless I'm confused, our bodies absorb O₂ from the atmosphere based on the partial pressure of the oxygen in each breath that we take. So this biological process is driven by density altitude, because it's the actual pressure that matters. Then again, I'm a Mechanical Engineer, and never even had high school biology, but did well in college Thermodynamics where such things are considered when burning hydrocarbon fuels . . . . .

I'm also thinking that my scariest flight was caused by 3 hours at 10,000 msl without supplemental oxygen, then finding storms near my destination. That's what pop-up IFR clearances are for, but it never occurred to me. The stiff drink with my "good" whiskey when I got home really hit the spot and settled me down, though. No more long, high trips like that for me, especially at the end of the day.

[aviatoreb]

4 minutes ago, Hank said:

Unless I'm confused, our bodies absorb O₂ from the atmosphere based on the partial pressure of the oxygen in each breath that we take. So this biological process is driven by density altitude, because it's the actual pressure that matters. Then again, I'm a Mechanical Engineer, and never even had high school biology, but did well in college Thermodynamics where such things are considered when burning hydrocarbon fuels . . . . .

I'm also thinking that my scariest flight was caused by 3 hours at 10,000 msl without supplemental oxygen, then finding storms near my destination. That's what pop-up IFR clearances are for, but it never occurred to me. The stiff drink with my "good" whiskey when I got home really hit the spot and settled me down, though. No more long, high trips like that for me, especially at the end of the day.

Your argument seems to make sense to me - its what I would guess - its a lot like a normally aspirated engine works.  However I would love to hear what ilovecornfields has to say on the topic since he is a flying actual doctor who is specifically interested in the topic.

[Hank]

21 minutes ago, aviatoreb said:

Your argument seems to make sense to me - its what I would guess - its a lot like a normally aspirated engine works.  However I would love to hear what ilovecornfields has to say on the topic since he is a flying actual doctor who is specifically interested in the topic.

@ilovecornfields, what say you about indicated altitude vs. density altitude when considering supplemental oxygen usage? The rest of us here are just guessing, or at least I am!

[ilovecornfields]

According to Flying magazine it’s pressure altitude, not density altitude they matters but that doesn’t seem to mirror my experience. I’m not sure what the right answer is.

https://www.flyingmag.com/technique-proficiency-technicalities-hypoxia-your-fingertips/#:~:text=It is important to note,various membranes in the body.

 

Here’s a more technical paper:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1114067/

[jaylw314]

1 hour ago, ilovecornfields said:

According to Flying magazine it’s pressure altitude, not density altitude they matters but that doesn’t seem to mirror my experience. I’m not sure what the right answer is.

https://www.flyingmag.com/technique-proficiency-technicalities-hypoxia-your-fingertips/#:~:text=It is important to note,various membranes in the body.

 

Here’s a more technical paper:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1114067/

I can sort of see that since density altitude is usually due to higher temp, and higher temps actually increases the height of the proverbial air column.  Haven't thought that one through though

[kortopates]

My layperson thought experiment suggest density altitude isn’t important but pressure altitude is since the body is more or less regulating the temperature at the membrane where it’s all about partial pressure of O2.
But just a guess.


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[tgardnerh]

7 hours ago, ilovecornfields said:

According to Flying magazine it’s pressure altitude, not density altitude they matters but that doesn’t seem to mirror my experience. I’m not sure what the right answer is.

https://www.flyingmag.com/technique-proficiency-technicalities-hypoxia-your-fingertips/#:~:text=It is important to note,various membranes in the body.

 

Here’s a more technical paper:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1114067/

Which direction is your experience--do you find that for a given pressure higher DA means worse oxygen saturation? On first principles (and per my wife, who did a year of anesthesia before switching to IM), the air at the alveolar membrane is 98.6 degrees and 100% RH, so ambient temperature *shouldn't* matter.

But also a stunning number of things in medicine that come down to "ehh, it seems like this causes that, nobody knows why," so I know better than to trust first principles here.