Austintatious

fun and scary day at FL210

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I am wondering if anyone makes an SpO2  sensor with an alarm function built-in that could be connected to the audio panel?   This, along with flow rate monitoring, could add a level of redundancy in a situation where seconds count.

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I am wondering if anyone makes an SpO2  sensor with an alarm function built-in that could be connected to the audio panel?   This, along with flow rate monitoring, could add a level of redundancy in a situation where seconds count.

Yes, we talked about a new finger device, that you actually wear on your thumb, that alarms by vibrating unmistakably when your O2 Sat level falls to below whatever you set it too. It gets your attention well before any hypoxia sets in.
See https://www.amazon.com/ViATOM-Wearable-Rechargeable-Saturation-Vibration/dp/B07MXZGVNW


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I agree with Dan and Erik, those of us flying high need a more serious O2 backup such as the MH product I also use. Why? It's not realistic to assume you can always point the nose down. If you use the FL's to add to your utility and to enable you fly above weather you may need to wait or divert for a ways before adding another emergency to deal with. The MH product gives you O2 with a better applicator (mask) and for quite awhile. (Although I don't know the specifics). But you know it's got much more pressure since it needs a regulator to dispense.
Thanks to skip for looking up the specs on the cans.


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All of you in SOCAL should come down to our PROTE event at SEE 11/20-11/24!
See FAASafety.gov for announcements.


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Second source and continuous pulse ox would be an absolute requirement - D tank or whatever  - if I were to spend time in an unpressurized vessel above 17k.  

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1 hour ago, bradp said:

 

Second source and continuous pulse ox would be an absolute requirement - D tank or whatever  - if I were to spend time in an unpressurized vessel above 17k.  

I've always been confused as to why any of those extra high altitudes are under a minute.  I can easily hold my breath under water for 2 minutes.  The world record is 22 minutes.  So how can it be 9-15 seconds at 45,000 ft?  I am not doubting those numbers, but it means I just don't understand this aspect of aeromedical factors. Can anyone explain my paradox confusion>?

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8 minutes ago, aviatoreb said:

I've always been confused as to why any of those extra high altitudes are under a minute.  I can easily hold my breath under water for 2 minutes.  The world record is 22 minutes.  So how can it be 9-15 seconds at 45,000 ft?  I am not doubting those numbers, but it means I just don't understand this aspect of aeromedical factors. Can anyone explain my paradox confusion>?

Not a doc, but there are TWO differences that come to mind vs. 'holding your breath.'  One, you don't realize the oxygen is NOT in the atmosphere you are breathing and you breath it OUT of your lungs.  Two, the partial pressure at altitude is very low (doh!), there's not as much O2 even if you do hold your breath it's not going to last 'as long.'  I imagine these tables assume you are breathing, not holding your breath.

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24 minutes ago, aviatoreb said:

I've always been confused as to why any of those extra high altitudes are under a minute.  I can easily hold my breath under water for 2 minutes.  The world record is 22 minutes.  So how can it be 9-15 seconds at 45,000 ft?  I am not doubting those numbers, but it means I just don't understand this aspect of aeromedical factors. Can anyone explain my paradox confusion>?

How much oxygen content is is your lungs when you hold your breath at sea level and how much is in your lungs when you hold your breath at 45,000 feet?  I could theoretically have someone breathe 100% oxygen for 15 minutes (wash out all the nitrogen in their lungs and replace it with oxygen)  then put them to sleep, paralyze them, go to the cafeteria and get a coffee and come back and intubate them and their oxygen level would be above 92%. The biggest factor is how much oxygen content is stored in your lungs when you hold your breath (and how rapidly you’re using it up).

 

944A70F5-4170-4548-9B61-4E35CEB5F8BC.jpeg

Edited by ilovecornfields

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Just now, ilovecornfields said:

How much oxygen content is is your lungs when you hold your breath at sea level and how much is in your lungs when you hold your breath at 45,000 feet?  I could theoretically have someone breathe 100% oxygen for 15 minutes (wash out all the nitrogen in their lungs and replace it with oxygen)  then put them to sleep, paralyze then, go to the cafeteria and get a coffee and come back and intubate them and their oxygen level would be above 92%. The biggest factor is how much oxygen content is stored in your lungs when you hold your breath (and how rapidly you’re using it up).

 

944A70F5-4170-4548-9B61-4E35CEB5F8BC.jpeg

My sick kids get about 15-30 seconds despite pre-oxegenation.  They wouldn’t do too well at FL-210.   Low FRC is the pits. 

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21 minutes ago, ilovecornfields said:

How much oxygen content is is your lungs when you hold your breath at sea level and how much is in your lungs when you hold your breath at 45,000 feet?  I could theoretically have someone breathe 100% oxygen for 15 minutes (wash out all the nitrogen in their lungs and replace it with oxygen)  then put them to sleep, paralyze them, go to the cafeteria and get a coffee and come back and intubate them and their oxygen level would be above 92%. The biggest factor is how much oxygen content is stored in your lungs when you hold your breath (and how rapidly you’re using it up).

 

944A70F5-4170-4548-9B61-4E35CEB5F8BC.jpeg

True that - but I am imaging those tables are read as 9-15 seconds at 45,000 ft assuming all was good - good o2 availability which is suddenly removed.  Just like dunking under water.  I should do that test with my finger sat tester.

Testing just now not preparing to hold my breath - here on my couch - yeah its tough just suddenly stop breathing after about 30 seconds!  But Im not passing out in 9.

So I still don't understand.

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I’ll have to do some math but it may be that the diffusion gradient becomes negative - ie you lose oxygen from your blood with tidal breathing at those extreme low partial pressures of oxygen (ie high altitude)

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9 minutes ago, bradp said:

I’ll have to do some math but it may be that the diffusion gradient becomes negative - ie you lose oxygen from your blood with tidal breathing at those extreme low partial pressures of oxygen (ie high altitude)

Could be it!

Does that mean it would be better (re time of consciousness) to hold your breath at 45,000 ft than to try and breath?

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If you make a rapid descent in emergency conditions, what are your plans not to swap paint with the plane below you.   Can a controller clear enough airspace for you?   Or is it see and avoid?

I am just asking, and trying to challenge you.   I will stay lower.  
Ron

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20 minutes ago, Ron McBride said:

If you make a rapid descent in emergency conditions, what are your plans not to swap paint with the plane below you.   Can a controller clear enough airspace for you?   Or is it see and avoid?

I am just asking, and trying to challenge you.   I will stay lower.  
Ron

Good question, generally it falls into the "big sky, small airplane" category.  If the other airplane is a jet, their TCAS will give them instructions to avoid.  If it's a small airplane, the real likelihood at those altitudes is that there just aren't a whole lot of other airplanes around.

So again, big sky, little airplane.

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At high altitude during a rapid or explosive decompression one can not hold ones breath due to the lowering of the ambient air pressure  surrounding the subject.  All the available "air" is forced out of the lungs to balance the pressures between the outside and inside of the lungs. In addition to the 4 normal types of hypoxia (Hypoxic Hypoxia, Hypemic Hypoxia, Stagnant Hypoxia, Histoxic Hypoxia) (we are only talking about Hypoxic Hypoxia in this discussion) there is another form called "reversed diffusion" or "fulminating hypoxia" that occurs when the air is forcibly removed from the lungs by a rapid decompression. This causes the TUC to be further reduced by 1/3 to 1/2 normal TUC times. 

This is why any RD or explosive decompression at high altitude is so dangerous (especially above 35,000' and it is why the very first memory item on any jet check list is "Don O2 Mask Immediately" "Make sure it is set to 100%" (which it should have been on preflight).

Up real high (again above usually 30000 to 35000' the mask automatically goes into what we refer to as "Pressure Breathing Mode" whereby the mask actually forces O2 into your lungs at an elevated pressure so that there is enough pressure (so that the "partial pressure of the O2 is high enough) to force O2 across your lung surface and into your blood stream.

Partial Pressure

In short, O2 makes up about 20% of the atmosphere and Sea Level pressure of the air is about 14.7 psi. SO therefore the O2 accounts for about 20% of the 14.7 psi or about  3.0 psi of the air pressure. When at 18,000' we are above @ 50% of the atmosphere and have about 7.3 psi air pressure. O2 gives us about 1.5 psi of that air pressure. 

You can see that the pressure available to push the O2 across the lung membrane is way low at 18,000' and worse the higher you go. So taking a deep breath at altitude while it may help a little (more of the weak O2 molecules touching the lung surface) the pressure to push them effectively across the membrane  just isn't there. So, maybe a little help but in reality the only thing that really helps is a higher concentration of O2  being inhaled (up to certain limits of altitude with out 'pressure breathing") and only with pressure breathing at very high altitudes. 100% O2 at ambient pressure and at very high altitudes will do nothing as the partial pressure is so low no O2 is transferred to the blood steam. 

Just for thoughts-   How good do you think those little Mickey Mouse O2 masks that drop down on commercial flights will work at 41,000'' if the 757 has an RD?   Think about that one for minute!

Secondly, even at the low 20s a loss of O2 is a real emergency!! Don't waste time trouble shooting the issue. You may never resolve it. And, an EMERGENCY DECENT is NOT done at 800 feet per minute. To hell with the supposed shock cooling, pull the power to idle and get your butt down as fast as you can! Its nothing to play dainty about. 

Also, everyone has their own "resting" physiological altitude. Even if you live right at sea level your body may metabolize O2 as if you were really at say 4,000'. Then when you go fly up to say 9.000' your body really thinks it is at 13,000' . Everyone is different and everyone has a different resting altitude. 

I've had 3 for real RDs in jets in my career (and 1 in an MU-2) (ya I had a few junk jets in the career {all 121s though}) and I can tell you it was dump the power and the nose and get down time. We didn't screw around. With cabin climbs in excess of 6000 fpm you don't have time to lose. Same goes for mid 20s non-pressurized as you really don't know when the clock started ticking on your PERSONAL TUC. TUCs only apply if you have a for real marker of when the O2 stopped (like an explosive decompression). In our Mooneys you really don't know how long it has been since the O2 system went down.

If you haven't taken a chamber ride to find your own tolerance for hypoxia you're not safe at altitude, period IMO!!!!

Get in line and get it done, no excuses.

My sermon- You're not a safe pilot until you have been tempered and you're not tempered until you do something in an airplane that scares the living S%^& out of you and YOU know you did it to yourself. Flying takes on a whole new perspective after that. 

As an aside- In WWI fighter pilots routinely flew up to 18,000 to 20,000 feet without O2 (they didn't even know about it) and stayed there for 1 hour or more. They all complained of various deficiencies upon returning to earth and we'll never know how many never woke up until impacting the ground out of control. Remember, they were young and very healthy pilots who's average life span in WWI was 1 to 3 weeks. How good of shape were they in after cruising at 18,000' for a period of time and then going down to 14,000 or 15,000 feet to dog fight? 

 

 

 

Edited by cliffy
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1 hour ago, Ron McBride said:

If you make a rapid descent in emergency conditions, what are your plans not to swap paint with the plane below you.   Can a controller clear enough airspace for you?   Or is it see and avoid?

I am just asking, and trying to challenge you.   I will stay lower.  
Ron

My experience from many flights and many hours between 20K and 26K (depending on wind, weather and direction), there is very rarely anyone within 10K feet above or below. Secondly, I'm in class A and therefore on an IFR flight plan. 

I'm 100% sure I could push the button and immediately descend at my pre-set 1000 ft/min without "swapping paint" with any other aircraft. I will undoubtedly have to explain myself upon reaching thicker air. But that is the least of my concern in that situation. And a recent conversation with a FSDO validated that they are happy for me to check in and explain the situation after the fact without any penalty. ATC would much rather be clearing traffic for you in a controlled but unannounced descent rather than clearing traffic for an unresponsive aircraft cruising along in the flight levels.

Paul @kortopates does make a great point about weather. I recently had a situation where I ran into ice at FL230. It didn't look like I'd be able to climb out of it and needed to descend. It took some time to carefully work my way down from FL230 to 16K as I needed to stay out of the visible moisture that was building all around me.  An O2 emergency in that situation would have certainly complicated matters. 

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https://www.youtube.com/watch?v=nPX2GR-zMNc

If you want something graphically presented watch this video and you'll see how fast and insidious hypoxia can sneak up on you.

Watch as his speech is slurred and his responses give way quickly.

Watch how he doesn't quickly take command of the situation and declare and emergency.

And he was in the mid 20s when it all went down. 

In a for real emergency NEVER ask permission from ATC (take command of the situation), DO what you need to do and then communicate and let them sort the traffic out.

Remember you only have to miss anyone by a few feet ATC is working in miles of separation. Chances of hitting another airplane are nil. 

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If you make a rapid descent in emergency conditions, what are your plans not to swap paint with the plane below you.   Can a controller clear enough airspace for you?   Or is it see and avoid?
I am just asking, and trying to challenge you.   I will stay lower.  
Ron

I believe APs that auto descend turn 90°, the thinking is your probably on airway, so 90° should be clear space.


Tom

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There was mention of a pilot incapacitation detection as a future feature with the garmin autoland video.  There would be ability to detect alarms such as cabin altitude  - hypoxia and incapacitated the plane lands for you avoiding terrain and alerting ATC.  

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7 hours ago, cliffy said:

https://www.youtube.com/watch?v=nPX2GR-zMNc

If you want something graphically presented watch this video and you'll see how fast and insidious hypoxia can sneak up on you.

Watch as his speech is slurred and his responses give way quickly.

Watch how he doesn't quickly take command of the situation and declare and emergency.

And he was in the mid 20s when it all went down. 

In a for real emergency NEVER ask permission from ATC (take command of the situation), DO what you need to do and then communicate and let them sort the traffic out.

Remember you only have to miss anyone by a few feet ATC is working in miles of separation. Chances of hitting another airplane are nil. 

That was really disturbing. This has come up so often, but there’s really no reason NOT to declare an emergency. Maybe the hypoxia hit early before the transmissions start. I guess that’s part of why they require the high altitude endorsement.

Couldn’t agree more about telling and not asking what to do in an emergency. ATC is great and they try to be helpful, but they’re not in the pilot’s seat and there’s a reason the PIC has the final authority and not someone else.

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Got another question or two-

For those planning on "pushing the button:" and letting the autopilot handle everything are you really thinking that you will accept passing out (by descending slowly) and hoping that the autopilot does the trick and saves you IF you wake up  at a lower altitude?

Just thinking about the thought process instead of pulling power all the way off and descending at red line to get your butt down while fully conscious. 

We can do that in the big iron (push the button and spin the dial) but we have good O2 masks on and working and we spin the dial a lot higher than 800 FPM and we hit red line. 

Does anyone go high with passengers?  If you do have you ever investigated your passengers personal health (pulmonary, heart issues) before you go up? Maybe you could handle it medically but can they? How about rear seat passengers having their O2 shut off in flight. How will you know they are hypoxic and not just sleeping? How will THEY know they have a problem? Might be  life or death situation.

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For rapid descents, don’t forget the commercial spiral. 

I did my single engine commercial in my Mooney. 

I did my spirals with gear down, flaps down, speed brakes out, power at 15 inches and 90 KTS. If I recall, the descent rate was like 2000 FPM. It would come down even faster with the engine at idle or more bank.

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1 hour ago, cliffy said:

Does anyone go high with passengers?  If you do have you ever investigated your passengers personal health (pulmonary, heart issues) before you go up? Maybe you could handle it medically but can they? How about rear seat passengers having their O2 shut off in flight. How will you know they are hypoxic and not just sleeping? How will THEY know they have a problem? Might be  life or death situation.

Perhaps you missed my post about how if you fall asleep in my plane you wake up with a pulse ox on your finger...

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45 minutes ago, N201MKTurbo said:

For rapid descents, don’t forget the commercial spiral. 

I did my single engine commercial in my Mooney. 

I did my spirals with gear down, flaps down, speed brakes out, power at 15 inches and 90 KTS. If I recall, the descent rate was like 2000 FPM. It would come down even faster with the engine at idle or more bank.

I've practiced emergency spirals in my C from 15,000 msl (later calculated that DA was 18,800), at cruise speed, clean, 45° bank and was hovering near 2000fpm. Seems it was a little higher descent rate below 10,000. No, I didn't spiral all the way down, just a couple of thousand feet at a time; seems we did two spirals and two straight ahead, near-redline descents (lots of airflow noise there!). A fun afternoon with a -II and an oxygen bottle.

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22 hours ago, exM20K said:

Nope. We were all trying to not get stupid in the PROTE.  Only one of six was able for any period of time > 3 mins.  IIRC the PROTE was at 29,000

-dan

In our chamber experience and the ones prior it was the younger pilots dropping out.  He took us to 6 minutes which I think they normally do 5.   My thing is loss of time.  I kind of auto went into deep breathing from the onset.  Did not care about doing math, but that is normal.

 

Seems like a M2 bottle and a mask in your lap would be a pretty good Back up

 

Edited by Yetti
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