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High altitude flight

tkatc

tkatc

Well Known Member
I did something stupid today and I'm man enough to admit it. (Or stupid enough, take your pick). There are clearly not enough posts in this section.

I was planning a flight from Florida to New Jersey today. The weather south of my airport was VFR. The weather at my destination was severe clear as well. Only problem was a system covering about 300 miles of ground that I didn't feel comfortable bobbing and weaving from underneath. I thought I would have to cancel but realized there was a chance I could go over the top. (Controversial to some of course). With the threat of worse weather over the next several days my getthereitis started to kick in. I figured I could take a local hop and see if I could get on top.

Usual departure, climbed out and found blue skies through some large broken areas. I was on top by 5000' or so. I climbed to 8500 to take advantage of some stronger tailwinds. So far so good. It was quite beautiful and smooth up there. I came upon some towering clouds and decided I could hop over. Up to 10,500 I went. Looking good. But the clouds kept rising...and me with them. I was lured on by some broken opaque holes where I could see the ground if I needed to escape. Next thing I know I'm flirting with 16,000 to rise above a small area. I was able to dip back down into thicker air but only to have to climb over some towers again. I had only gone this high before to top some remnants of the Rocky Mountains but was able to descend quite quickly after clearing the terrain. I remembered the rules about O2 and hypoxia but couldn't recite them verbatim. They are as follows for anyone needing a refresher:

(a) General. No person may operate a civil aircraft of U.S. registry --

(1) At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration;

(2) At cabin pressure altitudes above 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen during the entire flight time at those altitudes; and

(3) At cabin pressure altitudes above 15,000 feet (MSL) unless each occupant of the aircraft is provided with supplemental oxygen.

Anyway, I was above 15,000 for a substantial amount of time without oxygen. Bad move on my part and I could think of no better place to confess my sins. This mistake was fortunate for me as I returned home to NJ safely but I figure this post would be a good reminder for others to prepare properly so you won't sin in a similar fashion. Please feel free to discuss... :eek:
 
What was your density altitude? Your "cabin" pressure may not have been as high, or low, as you think. ( Incorrect Assumption - see posts further down)
Karl has some good advice about the NASA form and it is not too late to fill one out.
 
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A side note

Many of us here in Colorado LIVE at altitudes that many of you commonly cruise. Whereas the regs state that: . . "flight crew is provided with and uses supplemental oxygen".. . it does not address how much oxygen to use. I realize that the manufacturers have instructions with their equipment but it's a one size fits all approach. I never fly at altitude without a pulse oximeter for everyone on board. It is amazing how huge the difference in physiology is between people and how much even my own oxygen use changes from time to time.
The regs are behind the times IMHO. Something to consider if you're going to be flying high regularly.
My two cents.
 
The model (Digit) that I have, I believe is no longer made. Purchased thru a medical supply company by a MD friend; it was fairly expensive. The current generation is as good or better and less expensive, like many electronics. I know that several years back Aviation Consumer reviewed a few models. As I recall, the ones sold by Aeromedix ( www.aeromedixrx.com/ )were always held in high regard.
Maybe someone with more current knowledge can help.
 
Well, I was wrong; they still make the model of oxymeters I have but the price is a little better now although still not "cheap". I found them here:
HTML: 
http://www.modomed.com/cgi-bin/frontrunner.cgi?ri=100&rc=MODO&rs=T&ro=T&pln=MX&pid=MXPO&pm=&in=BCI3420Y&whs=ALL&os=NEXTAG&ctc=1
Mine are about 9 years old and work great. The batteries last forever. Sometimes I use one while working out. Not for the oxy % but for the pulse rate, when I don't want to wear the chest band.
 
As advised, I filed a NASA report. I understand why people want to remain anonymous with regard to this type of admission. After making the original post I felt I should have kept it to myself but would that help anyone? It's a shame we live in the sort of culture that is punitive vs encouraging open dialect but I think that is changing. I feel like the FAA is moving closer to a safety culture rather than the old "blame game". Controllers now have a program called ATSAP that allows them to self report safety issues without fear of punitive/disciplinary measures. The program compiles data and it seems to be working quite well. This compiled data has lead to changes in policy/procedure to enhance safety.

I hope it is clear that I did not post to brag but rather educate/remind.
I've received a couple of PMs thanking me for the refresher while admitting they have stories but are too scared to post them. Perhaps we could post these sort of stories anonymously? I'm sure there would be a few I could learn something from.
 
It affects everybody differently and isn't as damaging if you don't move around a lot. Easier on the younger. I use O2 above 9500 but once sat right seat up to 15,000. Felt fine until I tried to reach into the back seat - almost passed out.....
If you're gonna fly a lot get O2. More important than a lot of toys we buy. :rolleyes:
 
tkatc said:
As advised, I filed a NASA report. I understand why people want to remain anonymous with regard to this type of admission. After making the original post I felt I should have kept it to myself but would that help anyone? It's a shame we live in the sort of culture that is punitive vs encouraging open dialect but I think that is changing. I feel like the FAA is moving closer to a safety culture rather than the old "blame game". Controllers now have a program called ATSAP that allows them to self report safety issues without fear of punitive/disciplinary measures. The program compiles data and it seems to be working quite well. This compiled data has lead to changes in policy/procedure to enhance safety.
Click to expand...

I hope the same happens for the medical. I know many people that are too scared to see a doctor for fear of finding something that makes them loose their medical. That sounds like FAA medicals do not promote good medical behavior. I hope the FAA culture is a changing to safety and not just rule following.

Sorry for the short thread hijack. Back to the original topic.
 
Thanks!

You might be questioning yourself for posting this, but you might have just saved some lives! We can all be lulled into doing something potentially dangerous. Well worth it in my opinion.
 
Just a comment about the Nonin brand of oxymeter. I've got an 12 year old medical one and lost the battery cover. I called them and they promptly sent me a new one, free.

Very impressive customer service.

Dave
 
Thanks for posting and yes this section of our forum is seriously lacking posts. Maybe most RV guys really are perfect.

We have used portable O2/pulse oximeter over the top three times in our -10. We don't leave home without it on any overnight long xc trips. I notice changes in myself above 10K. SkyOx has been worth every penny.
 
With regard to an earlier post: it is pressure altitude, not density altitude, that matters. This is one place where the FARs got it right ("cabin pressure altitude"). Inside your lungs the O2 exchange rate doesn't care about the density, it's the partial pressure that matters.

I personally feel that if you don't carry oxygen and a pulse-oxymeter with you on x/c trips you are limiting your options.
 
Look up the Mountain High folk, buy a system.

Learn how to get your plane to perform right up there too.

Its a nice part of the sky to be in actually.:)
 
yep, if you have a plane that will go to 18K and you do long xc trips an O2 system is a must. clear thinking is a nice thing to have up there.

tony, what were the meters reporting in that 300 mile section? :)
 
I think I'm going to change my W&B and keep the O2 bottle on board all the time. I've always said "I'll carry O2 when going east-west." But this thread shows there's no reason to think it won't be helpful flying north-south.
 
In my 1400 hours of flying I still find interesting and unexpected WX situations. I think weather is one of the hardest parts of flying to teach and most learn what it really means in our flying through experiences. Having an IFR rating and staying current is a great step to help and allows you to tempt otherwise questionable weather plus makes you a much more precise and confident pilot when things go downhill...or in this case uphill. A few years back on the way to OSH there were three of us flying in loose formation and we hit what looked like an unforcasted very thin cloud layer at our 5500' altitude. It was also somewhat hazy so visibility was only about 10nm at best but enough to hide the clouds beyond. I decided to go over and the other two guys, not IFR rated went under with us expecting to meet up on the other side. Well, it turned out to be a cloud that continued to grow up and down. My two buddies were skirting under down to 1500' and I started a long climb and topped out at 11,500 and ready to file a popup IFR plan to get down or through knowing I didn't want to go much higher without O2. Fortunately that was the trailing edge of that cloud and it thinned out so down I went and up my wingmen went with both of us meeting up as planned. The point is, no one could have taught me about that situation and it had to be experienced so now I know. The IFR rating is also reassuring to have and there has been an instance it has come in handy getting into unexpected IMC. I also know that there will be more to learn as time goes on.

Glad to hear you made it through safely and building experiences to add to your knowledge base.
 
On Board Oxygen - Required Equipment in RVs

The service ceiling of most non-turbo factory singles makes on-board oxygen somewhat of an un-needed luxury. The capability of the RVs almost make oxygen a required element. Why limit yourself to about half of the plane's flight envelope for the sake of a couple of hundred dollars? Other than thunderstorms, most of the weather we face is below 10,000 feet. On top is good. Better yet, why waste a 40 or 50 knot tail wind if it's up there where the plane can get to it?
If your mission is limited to local flights, oxygen may be overkill (so perhaps is synthetic vision, HITS, etc.). If you really plan to use your RV for X-country, then add it to the required list of equipment. Use it above 10,000 (especially if you're over the age of 30), and use it at night at lower altitudes and during landing phase.
Finally, the original post addressed the issue of judgement. It won't get better at higher altitudes without supplemental oxygen.
Terry, CFI
RV9A N323TP
 
Lightweight Bottles

If weight is a problem, go to a Kevlar or Carbon Fiber bottle. I got a Mountain High KF-022 kevlar fiber wound 22 cu ft bottle, pulsed oxy delivery, etc, and the whole thing weighs just under 4.5 lbs. I just papoose it in my -4 behind my seat. 22 cubic ft is a lot of O2!! It lasts a long time between fills.

I regularly make trips of 400 to 500 miles from 8 to 12 thousand feet & go on it right away. I use it even if I'm hanging at 6,500'. Why not??? I promise you, you will feel better when you get to your destination. Now, I live at 130' above msl, so I'm not used to altitudes.

To me, it is such an easy fix and is painless. I fill my own tank out of my welding bottle. I don't understand any reticence or hesitation to equip yourself somehow, with O2...other than cost???:confused: But considering the safety and absolute necessity for it, just do it. The papoose bottle is no more of a hassle than bagging your headsets IMO.

Just my 2 centavos. Wishing us all happy & safe flying.

Cheers,
 
I am a curious about the physical effects of flying at altitude. I am a flat lander currently flying a C172 for XC and I used to fly at 8k or 9k and seemd like after a 3 hour flight I was very tiered. I have dropped that down 1k to help. I assumed I would get Ox fro the RV even if flying at 10k-12k just for that reason. Any one else? I can't imagine how tiered I would be after a flight at 15k with no ox.
 
BobTurner said:
With regard to an earlier post: it is pressure altitude, not density altitude, that matters. This is one place where the FARs got it right ("cabin pressure altitude"). Inside your lungs the O2 exchange rate doesn't care about the density, it's the partial pressure that matters.

I personally feel that if you don't carry oxygen and a pulse-oxymeter with you on x/c trips you are limiting your options.
Click to expand...

I think there is a lot of misunderstanding here Bob as I have been told differently, and both ways. I really want to understand this.
At higher density altitudes you have less oxygen per whatever unit of measure you want to use. So if I understand you correctly, it does not matter the amount of oxygen in the air as we are physically limited by our lungs ability to exchange it based on pressure? If this is correct, why does adding oxygen through my canula matter? I don't think it raises the pressure of the air I am breathing only the amount of oxygen. Does it raise the O2 in such a gross manner that my lungs overcome the pressure inefficiencies?

PS - even if the FAR's got that part right I would be curious to know why they selected the altitudes they did for the regs. Sherpa's can climb Mt. Everest without O2, some people get sick at 7Kft.
 
Pardon my ignorance, if these are silly questions, but I looked across the forums, and don't see anything relating to O2 systems.

If I buy a system, am I legal to use it at my discretion, or does it need to be inspected or checked out by anyone besides myself? Is there a checkout or sign off I need in order to use it above 15k? I know there is a high altitude endorsement, but I believe this only applies to flight above 18k.

I fly West to Vegas every once in a while, and flying over mountains with only 1500 clearance makes me nervous.
 
O2 Saturation limit

JonJay said:
I think there is a lot of misunderstanding here Bob as I have been told differently, and both ways. I really want to understand this.
At higher density altitudes you have less oxygen per whatever unit of measure you want to use. So if I understand you correctly, it does not matter the amount of oxygen in the air as we are physically limited by our lungs ability to exchange it based on pressure? If this is correct, why does adding oxygen through my canula matter? I don't think it raises the pressure of the air I am breathing only the amount of oxygen. Does it raise the O2 in such a gross manner that my lungs overcome the pressure inefficiencies?

PS - even if the FAR's got that part right I would be curious to know why they selected the altitudes they did for the regs. Sherpa's can climb Mt. Everest without O2, some people get sick at 7Kft.
Click to expand...

I am not sure about the first part but as far as the FAA altitude limits, I was told that it is based on an 85% O2 saturation level. I flew my first X/C last week using a friends Mountain High set up and it worked great, I was up at 17,500. I was an Air Force fighter guy in my first career and always had a mask so I did have to learn to breath through my nose and not my mouth so much. Fortunately I had been through the altitude chamber and know my hypoxia symptoms, but I learned a new one which is a twitch in the muscle near my eye.

The Pulse Ox meter is great to have it lets you adjust the O2 based on your needs. At 15,500 the bubble gauge on the Mt High system was more O2 than I needed, I could reduce the flow and keep my O2 at around 90% and felt good.

I will be getting a system but I need to find out how RV-8 guys fit these tall bottles. For my solo trip it was lying down beside me on of my tent but with a PAX this would not work. I will have to search the forum to see how guys fit them. I am thinking the bottle will need to be in the forward baggage area and plumbed to the cockpit but maybe not.

We all try dumb things once in a while the old saying what does not kill you makes you better. But the first post is also what makes us all better, passing on things one has done that was not so smart will pop into the heads of those that have not been down that road. Thanks for you honestly and input.

Cheers
 
High flight...

In 1999 I was with a group of EZ pilots returning from deep southern Baja CA. Off the coast of Lareto, a couple of the guys got mixed up in weather. Both IFR pilots, both without O2, decided to try to climb out the top of the weather. Last report from one of the guys was at 17,000 ft. He died, crashing in the Sea of Cortez.

I've had a couple times in the EZ when I thought I'd be able to climb over a front I ended up around 18,000 for 15-20 min and barely squeaked over, and yes I was using O2.

High flight without O2 is serious business. When I decided to start taking advantage of high flight, I attended the Physiology / altitude training offered by the USAF to civilians. I did mine at Edwards AFB and it was an eye opener. I HIGHLY recommend that everyone who decides to operate where O2 is needed, should take that course. I think if you contact your local FSDO office, they can tell you where the training is offered in your area.

In my 30's I could fly for hours at 12,000 without noticeable side effects, in my 40's that threshold dropped to 10,000 ft, in my 50's it's even lower. Now, after an hour at over 10,000 ft I get a hypoxic headache that takes HOURS to go away even after landing. The biggest bang for the buck though is alertness you retain when using O2.

No headaches & no tiredness after a trip now. It's worth every penny at the end of the trip. Get the training & get the O2. It will be one of the best investments you'll make.
 
JonJay said:
I think there is a lot of misunderstanding here Bob as I have been told differently, and both ways. I really want to understand this.
At higher density altitudes you have less oxygen per whatever unit of measure you want to use. So if I understand you correctly, it does not matter the amount of oxygen in the air as we are physically limited by our lungs ability to exchange it based on pressure? If this is correct, why does adding oxygen through my canula matter? I don't think it raises the pressure of the air I am breathing only the amount of oxygen. Does it raise the O2 in such a gross manner that my lungs overcome the pressure inefficiencies?

PS - even if the FAR's got that part right I would be curious to know why they selected the altitudes they did for the regs. Sherpa's can climb Mt. Everest without O2, some people get sick at 7Kft.
Click to expand...

The answer is in partial pressure gas laws. Air is 20% O2 and 80% N2 at all altitudes. 18,000 ft is 1/2 the pressure of sea level, thus the equivalent partial pressure of O2 at 18,000 ft would be roughly 10% O2. By doubling the concentration of O2 at 18,000 ft you can restore it's partial pressure to sea level equivalent.

That's why in the Gemini/Apollo programs whey were using roughly 5 psi pure O2 in the capsule to create a sufficient partial pressure of O2 that humans need to drive the O2 molecule across the lung membranes.
 
JonJay said:
I think there is a lot of misunderstanding here Bob as I have been told differently, and both ways. I really want to understand this.
At higher density altitudes you have less oxygen per whatever unit of measure you want to use. So if I understand you correctly, it does not matter the amount of oxygen in the air as we are physically limited by our lungs ability to exchange it based on pressure? If this is correct, why does adding oxygen through my canula matter? I don't think it raises the pressure of the air I am breathing only the amount of oxygen. Does it raise the O2 in such a gross manner that my lungs overcome the pressure inefficiencies?

PS - even if the FAR's got that part right I would be curious to know why they selected the altitudes they did for the regs. Sherpa's can climb Mt. Everest without O2, some people get sick at 7Kft.
Click to expand...


Your basically correct about the partial pressure issue when breathing oxygen. In the RV world however we can't fly high enough where it matters. The canula system is just fine. The pressure issues only comes up when above 30,000 feet. Military oxygen system at very high altitudes revert to a pressure breathing system where it forces oxygen under pressure to overcome the issue you mention. Its very uncomfortable and makes it difficult to talk when pressure breathing. Its not a factor at our altitudes.

George
 
rv9av8tr said:
The answer is in partial pressure gas laws. Air is 20% O2 and 80% N2 at all altitudes. 18,000 ft is 1/2 the pressure of sea level, thus the equivalent partial pressure of O2 at 18,000 ft would be roughly 10% O2. By doubling the concentration of O2 at 18,000 ft you can restore it's partial pressure to sea level equivalent.

That's why in the Gemini/Apollo programs whey were using roughly 5 psi pure O2 in the capsule to create a sufficient partial pressure of O2 that humans need to drive the O2 molecule across the lung membranes.
Click to expand...

Thank you. That makes perfect sense.
 
sailvi767 said:
Your basically correct about the partial pressure issue when breathing oxygen. In the RV world however we can't fly high enough where it matters. The canula system is just fine. The pressure issues only comes up when above 30,000 feet. Military oxygen system at very high altitudes revert to a pressure breathing system where it forces oxygen under pressure to overcome the issue you mention. Its very uncomfortable and makes it difficult to talk when pressure breathing. Its not a factor at our altitudes.

George
Click to expand...

Partial pressure law is EXACTLY what makes a difference at RV flight altitudes. I think you are referring to the need to breath from a pressurized O2 source, which matters at altitudes where even 100% O2 isn't enough. 100% O2 at essentially no pressure has the equivalent partial pressure still of 0.

I don't know off the top of my head where that altitude breaking point is, but you're right, it's not where RV's can fly.
 
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To oversimplify, the human body requries both oxygen and oxygen under pressure pressure in the lungs to keep from experiencing hypoxia. Even if one is breathing 100% oxygen, the oxygen in the lungs must be under sufficient pressure (actually partial pressure) to facilitate passing the oxygen molecues from the lungs into the blood stream. If it is not, the oxygen does not pass and hypoxia ensures. In other words, at high altitudes it is quite possible to die of hypoxia while breathing 100% oxygen.

Pressure demand oxygen regulators take care of this by supplying oxygen at greater than ambient pressure which fills the lungs with pressurized oxygen, allowing the transfer of oxygen to take place. This is commonly called pressure breathing. All that said, the altitude where pressure breathing is absolutely required is quite high, above 40,000', if I remember correctly. I believe the F-4 oxygen regulator phased in pressure breating at 32,000'.

So what is the advantage of increasing oxygen content in breathing air at altitudes below those mentioned above? As altitude increases above sea level, the pressure decreases, decreasing the capability to pass oxygen molecules into the blood. The more oxygen molecules in the lungs, the more that can pass into the blood under this decreased pressure.

-John

JonJay said:
I think there is a lot of misunderstanding here Bob as I have been told differently, and both ways. I really want to understand this.
At higher density altitudes you have less oxygen per whatever unit of measure you want to use. So if I understand you correctly, it does not matter the amount of oxygen in the air as we are physically limited by our lungs ability to exchange it based on pressure? If this is correct, why does adding oxygen through my canula matter? I don't think it raises the pressure of the air I am breathing only the amount of oxygen. Does it raise the O2 in such a gross manner that my lungs overcome the pressure inefficiencies?

PS - even if the FAR's got that part right I would be curious to know why they selected the altitudes they did for the regs. Sherpa's can climb Mt. Everest without O2, some people get sick at 7Kft.
Click to expand...
 
RVG8tor said:
I am not sure about the first part but as far as the FAA altitude limits, I was told that it is based on an 85% O2 saturation level. I flew my first X/C last week using a friends Mountain High set up and it worked great, I was up at 17,500. I was an Air Force fighter guy in my first career and always had a mask so I did have to learn to breath through my nose and not my mouth so much. Fortunately I had been through the altitude chamber and know my hypoxia symptoms, but I learned a new one which is a twitch in the muscle near my eye.

The Pulse Ox meter is great to have it lets you adjust the O2 based on your needs. At 15,500 the bubble gauge on the Mt High system was more O2 than I needed, I could reduce the flow and keep my O2 at around 90% and felt good.

I will be getting a system but I need to find out how RV-8 guys fit these tall bottles. For my solo trip it was lying down beside me on of my tent but with a PAX this would not work. I will have to search the forum to see how guys fit them. I am thinking the bottle will need to be in the forward baggage area and plumbed to the cockpit but maybe not.

We all try dumb things once in a while the old saying what does not kill you makes you better. But the first post is also what makes us all better, passing on things one has done that was not so smart will pop into the heads of those that have not been down that road. Thanks for you honestly and input.

Cheers
Click to expand...
Mine is in the tall/deep, right side of my RV-8 forward baggage compartment.

Here is the setup in the cockpit.
rightfrontoxy_zps0fe9956a.jpg
 
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Sherpas...

As far as the Sherpas.... the body has the long term ability to compensate for high altitude by increasing your red blood cell count, but that takes months. Everest climbers typically stay at base camp (18,000 ft) for 3-4 wks before moving up the mtn.
 
This was a good post and I have learned a lot about things that where not exactly told to me correctly in the past. This is a good example of why posting things like this, while they may put you out in the open, are helpful to many of us.
Until I owned my RV, flying at any kind of altitude where it made a difference was simply out of the performance envelope.
 
ColoCardinal said:
... It is amazing how huge the difference in physiology is between people ...QUOTE]

+1!

In a previous life, I decided to see how high I could get my 170, and how long it would take. I took off from <100MSL and wrote down the time every 500 ft. At 14,500 (about 45 minutes, if you were wondering), I could plainly see my watch, but couldn't interpret its reading. I had just enough sense left to know what the problem was, and started down. I was down to 8,000 before before I felt like I had my wits about me again. I should have known better, as I have never blown better than 80% on a spirometer test. Iv'e known others that could go to 17-18,000 feet and still be functional. MY RV-7 WILL have oxygen, and I'll have a pulse oximeter onboard.
Click to expand...
 
I like that we are talking about prevention. (Thanks TK for getting us talking).

Here are some of my answers to questions above:

Where do RV-8 pilots install their O2 ?
Click to expand...
My system may not work for others as I have a pulse demand unit which means, if I'm not breathing, it's not flowing. Given that, my bottle is vertical in the well of the forward baggage compartment. It has a formed foam "footy" and a foam "ring" that keeps it from moving around but it is easy to install/remove.I know there are pros and cons to this location but it's what I have.

What about the physical effects ?
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My personal experience has been that I often find my flights at 10.5K and 11.5K. On the first leg of my trips, I don't notice the altitude (without O2) but suspect it is there. On later legs, I "feel" tired. In both cases, I "feel" the flight when it comes to the landing. Dropping from 10.5K to 8.5K is noticeable. In all cases, adding O2 makes me "feel" better.
 
Someone asked about legalities.
FARs:
Pilot on O2 above 14,000 anytime, or above 12,500 for more than 30 minutes.
Passengers must have it available (they can decline) above 15,000'.
Canulas are not supposed to be used above 18,000' but personally as long as I had a pulse oxymeter showing I was okay I might disregard this rule.
All altitudes are "cabin pressure altitudes" so in principle you should open an alternate static valve to the cabin and set the altimeter to 29.92. In practice using the altimeter as-is is close enough unless you are right at 12,500', etc.
The "high altitude" endorsement is for flying pressurized aircraft above a certain altitude, does not apply to RVs.
DOT:
Department of transportation regulates pressurized gas cylinders. There will be a test date stamped on your cylinder. Depending on what type (aluminum, steel, kevlar) it is there is a requirement for a pressure test after xx years. If you go past that date some (most?) operators will refuse to re-fill your cylinder. I forget the inspection period for aluminum, is it 5 years?
My story: as I went past age 50, I was at 11,500' at night. After a while I decided to go on O2. After one breath, I immediately noticed the colors on the ground. I had been seeing in black and white! (this is a well know symptom of hypoxia)
Mild amusement: if you are cruising and bored, put on your pulse oxymeter and experiment with breathing (no supplemental oxygen needed). You will be surprised by how effective slow deep breaths are, compared to short shallow ones. With shallow ones you tend to reuse the same air over and over, it never gets out of your throat.
Pressure masks: partial pressure of O2 at sea level is 20% of 15 psi, or 3 psi. So when the total atmospheric pressure is less than 3 psi 100% oxygen is no longer sufficient, and you need to go to a force- feed pressurized system. This is somewhere above 40,000'. Pretty high for an RV!
 
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Anybody use the active O2 systems, the ones that extract O2 from the air? Expensive, and not worth it if high altitude flight is not done regularly, just wondering.

BTW, the NASA ASRS "get out of jail free" form may not be as useful as we think. Years ago I busted a VIP TFR, was tracked down (not by F-16s), and when I told the FAA attorney that I had filed the form she said it didn't apply because I had knowingly busted the FARs (by not getting a proper briefing before takeoff). Likewise, the OP in this thread knowingly busted the FARs. I think the form may only work when you inadvertently dip a wing into controlled airspace or something.
 
terrykohler said:
The service ceiling of most non-turbo factory singles makes on-board oxygen somewhat of an un-needed luxury. The capability of the RVs almost make oxygen a required element. Why limit yourself to about half of the plane's flight envelope for the sake of a couple of hundred dollars? Other than thunderstorms, most of the weather we face is below 10,000 feet. On top is good. Better yet, why waste a 40 or 50 knot tail wind if it's up there where the plane can get to it?
If your mission is limited to local flights, oxygen may be overkill (so perhaps is synthetic vision, HITS, etc.). If you really plan to use your RV for X-country, then add it to the required list of equipment. Use it above 10,000 (especially if you're over the age of 30), and use it at night at lower altitudes and during landing phase. Finally, the original post addressed the issue of judgement. It won't get better at higher altitudes without supplemental oxygen.
Terry, CFI
RV9A N323TP
Click to expand...

This is a fanstastic point. One of my chamber rides included a night time demonstration only taking us up to 10K' off O2. I was floored at just how much my night vision had fallen off after 15 minutes, but didn't realize it at all until going back on the mask.
 
My experience

About 20 years ago, my wife and I departed VFR in our C-310 from Eagle, CO headed East to Chicago. I still remember the briefer's words: "You couldn't have picked a better day to go over the mountains."

Well, a few minutes in our climb, we were in snow showers in a canyon. With no time to file IFR, we continued climb while getting out the charts and requesting an IFR clearance. By the time we got our clearance we were skirting the tops at 14,000 ft.

Everything was going well ... then I remember remarking to my wife that "it must be raining outside; my hands are getting wet!" She thought my remark was crazy, but it made perfect sense to me at the time. Then, I realized that my thinking was definitely impaired. I suffered no headaches or other symptoms.

I immediately asked for lower, and when ATC asked me to they would have lower for me in another 20 miles or so, I informed them that I needed lower immediately due to no oxygen.

I got an immediate clearance. No paperwork required and no questions asked.

I bought a Nelson O2 system. It's relatively inexpensive and I consider it a safety feature. I'm now 71, and my service ceiling is much lower than my RV-8.

Cheers,

Rafael
 
Pulse/ Oxymeter

I've been following this thread with great interest, very educational.
I recently bought an pulse oxymeter because my wife mentioned a light headache
after flying a 10,000 feet for a while. I am also interested in what my own oxygen saturation would be at higher altitudes.
After reading all the info that came with the oxymeter I could not find any info on exactly what oxygen saturation should be. I understand more is better but specifically at what level should one be concerned?
Incidentally, I did experiment with deep breathing and noticed an increase in saturation almost immediately.
 
Same question here...

Wondering the same thing. I recently bought the Nonin GO2 Achieve, but have yet to fly with it. Here at 700MSL, the unit typically says 95-98%. At what level should we be concerned? And, with oxygen while flying, is it possible to get back to this same % that is seen here on the ground?
 
Jeff A said:
Wondering the same thing. I recently bought the Nonin GO2 Achieve, but have yet to fly with it. Here at 700MSL, the unit typically says 95-98%. At what level should we be concerned? And, with oxygen while flying, is it possible to get back to this same % that is seen here on the ground?
Click to expand...

90% is often used as a meaningful threshold for oxygen saturation. Of course, each of us responds differently, so you'd do well to creep up on that mark slowly.
 
My house is at 7200' and much of my work time is at 8000+. When we go skiing, we are up to 12,500. Just to get out of our valley to Denver, we can be at 14,000 and still run into things. I believe I am pretty acclimated to high altitudes and have no trouble skiing or biking where the air is pretty thin.

Even living and playing at altitudes a 172 has a hard time getting to, for me an oxygen system is as critical as ANY other instrument or avionics in my plane. It will be installed before any of the panel. The cost is so small, why chance it?
 
Jeff A said:
Wondering the same thing. I recently bought the Nonin GO2 Achieve, but have yet to fly with it. Here at 700MSL, the unit typically says 95-98%. At what level should we be concerned? And, with oxygen while flying, is it possible to get back to this same % that is seen here on the ground?
Click to expand...

In medicine we accept spo2 levels of 90% or greater and provide supplemental oxygen to levels of 89%.

In order to understand the second part of the question, you must understand partial pressures of atmospheric gasses, decreasing total atmospheric pressure and percent oxygen delivery of your mode of delivery (cannula, mask, etc.)

At sea level, total atmospheric pressure is 760 torr. O2 is 21% of 760 or 160 torr partial pressure O2. At 10,000 total pressure is 523 torr. At 15,000 total pressure is 429. At 20,000 total pressure is 349 torr.

A nasal cannula can deliver an effective O2 percent of 28-44% when running flow rates of 2-6 liters per minute. A non-rebreather mask with 10-15 liter per minute O2 flow rate will deliver 60-80% inspired oxygen.

So, running 2 liter flow at 10,000 feet: 28% x 523 = 146 partial pressure O2. Note the 146 is less than the 160 torr of room air partial pressure O2 at sea level. So, to deliver the same partial pressure O2, you would need to increase flow rate and/or use a mask to increase inspired oxygen concentration.

Those who live at high altitude live by the same rules as above, but the red blood cell will make an enzyme after a few days at altitude which increases the efficiency of the red blood cell. With the enzyme, the red blood cell may pick up more oxygen and drop off more oxygen thus the individual may tolerate lower partial pressures of atmospheric oxygen without becoming symptomatic.
 
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94% feels near normal to me.

92% is okay, but I'm off my game.

90% is like being tired or fuzzy. Alertness is off but I don't feel unsafe. If I am, and I probably am, I can't tell.

88% is not good. I know I'm not really up to being PIC. No danger of nodding off, but I'm doing more sightseeing than being a thinking pilot.

It takes more O2 than one might think to keep the level up at say 16,500, but a nasal cannula can handle even 18k. Just crank the flow right on up to what's needed.

My aim point is to try hold 93%. Success with that will depend on my own condition that day as well as the flight's task load. Usually, after a longish flight, I'll keep the high altitude O2 flow going until I'm off the active on the ground. I'll be tired from the flight, there will be turbulence and traffic and other things to deal with, and this helps me fly well with all that.

Dave
 
Medical Ox?

Is medical oxygen cheaper than ABO? I called the local airport, and they want $75.00 per fill on a D sized bottle. I might have to plead my case to my physician to see if I can get a prescription. I'd like to think that a reasonable doctor could see the benefit of oxygen for a pilot....

Don
 
As an Aviation Physiologist nothing better than a discussion of partial pressures to start the day.

Dave's pulse ox values are pretty good.

Don't rely on symptoms as your safety net. Chamber studies show a wide range range of pulse ox readings before hypoxia symptoms are noted. Ranges from 87pct to 67 pct with the average at 79. Mild but Measurable Performance effected below 94 with substantial mental performance degradation at 90pct.

USAF used Nonin for our F22 issues, not hypoxia but that's another story. Great company to work with. But their are plenty of great devices out their.
 
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oxygen

I read all the post here today and I hear alot of people say they use oxygen at or above even 9000msl. The truth is if you are in great shape, don't smoke your safty margin is very high. my airport in wyoming is at 7200msl. I fly quite aften around that 15000 to 16000' with out oxygen. I might be used to it a little more since I live at a higher altitude, but if you are crusing around at 12000' I wouldn't even worry about using oxygen. I think a lot of people worry about it to much that it starts playing with there mind. I always have it though on hand. To fly IFR you have to be at 12500' min. The clouds often times don't look as high as they really are and can suck you into thinking o just a little more; glad you made it back.:)
 
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