FAR 61.31g -Pressurized aircraft section

[Jaybird180]

Reading the above reference and I wondered if there are any non-pressurized airplanes certified above 25,000 feet?

2nd question: Why is 25k the magic number? I read somewhere about the death zone of 25-30k. Explain please.

 

[poadeleted20]

Reading the above reference and I wondered if there are any non-pressurized airplanes certified above 25,000 feet?

V35TC Bonanza and Cessna 401 are two.

2nd question: Why is 25k the magic number? I read somewhere about the death zone of 25-30k. Explain please.

That "death zone" is the issue. Above 25,000 MSL pressure altitude the time to serious physiological problems gets very short even when oxygen is provided to avoid hypoxia. The problem is that the ambient pressure is so low, that unless O2 is supplied under pressure, you can't get enough oxygen into the blood. See:
http://www.faa.gov/pilots/training/airman_education/media/IntroAviationPhys.pdf
...for more.

 

[Walt]

Jaybird,
Cessna T210 and Mooney TLS are certified to 25K. I have owned both and never saw a need to operate at that level. If something happens to the Ox system (it happens) you have a real emergency. Engines wear out quickly when they are operated in the mid 20's.

 

[Alexb2000]

T206H 27K. Never had one above the mid-20's.

 

[wabower]

I think my the service ceiling on my N-model T-210 was 27,500. I got it to FL190 one day for about 10 minutes when solo, and even when light the deck angle at that altitude was excessive. Wouldn't dream of trying to fly higher.

Reading the above reference and I wondered if there are any non-pressurized airplanes certified above 25,000 feet?

2nd question: Why is 25k the magic number? I read somewhere about the death zone of 25-30k. Explain please.

 

[Alexb2000]

One more Cessna 400 25K, will easily do it. I wouldn't be surprised if it could go above 30K.

BTW- The NAI record for aircraft under 3800 lbs. is held by a 210 at 42,344'.

 

[Apache123]

A turbo Twinkie is 30,000ft absolute ceiling I think

 

[Inverted]

Beech 99 is.

 

[poadeleted20]

BTW, despite the title of 61.31(g), that paragraph applies to any "aircraft that has a service ceiling or maximum operating altitude, whichever is lower, above 25,000 feet MSL" whether pressurized or not -- read the definition in the first subparagraph (I've confirmed with AFS-800 that they really wanted it to read that way that way). That means if you are flying any of those planes mentioned above, you must comply with 61.31(g) either by endorsement or grandfathering. Even if you want to quibble over the regulatory questions, from a safety perspective, you really need to know what happens to your body above that altitude even with supplemental O2.

 

[RotorAndWing]

BTW, despite the title of 61.31(g), that paragraph applies to any "aircraft that has a service ceiling or maximum operating altitude, whichever is lower, above 25,000 feet MSL" whether pressurized or not -- read the definition in the first subparagraph (confirmed with AFS-800). That means if you are flying any of those planes mentioned above, you must comply with 61.31(g) either by endorsement or grandfathering..

Please ask AFS-800 to put that into a memo on FAA letterhead and please sign it and give you a copy.

Even if you want to quibble over the regulatory questions, from a safety perspective, you really need to know what happens to your body above that altitude even with supplemental O2.

Don't disagree there.

 

[poadeleted20]

Please ask AFS-800 to put that into a memo on FAA letterhead and please sign it and give you a copy.

They don't have to and it wouldn't matter anyway. It's stated in the plain language of the regulation itself. I only asked about their intent, (I've edited my earlier post to make that clear), and that's what they told me, giving the reasons stated (with which you agreed), but that wouldn't matter much legally, so there's no need for or value in doing what you ask. If you (or anyone else) doubt the legal interpretation of that section, ask the Chief Counsel, not AFS-800, because AGC-200 is the only office whose opinion counts legally. I haven't asked them, and don't much care to, but you are certainly free to do so.

 

[RotorAndWing]

They don't have to and it wouldn't matter anyway. It's stated in the plain language of the regulation itself. If you (or anyone else) doubt that, ask the Chief Counsel, not AFS-800, because that's the only office whose opinion counts legally. I only asked about their intent, and that's what they told me, for the reasons stated (with which you agreed), but that wouldn't matter much legally, so there's no need for or value in doing what you ask.

It's not stated plain language in the regulation. It's ambiguous at best.

(g) Additional training required for operating pressurized aircraft capable of operating at high altitudes.
(1) Except as provided in paragraph (g)(3) of this section, no person may act as pilot in command of a pressurized aircraft (an aircraft that has a service ceiling or maximum operating altitude, whichever is lower, above 25,000 feet MSL), unless that person has received and logged ground training from an authorized instructor and obtained an endorsement in the person's logbook or training record from an authorized instructor who certifies the person has satisfactorily accomplished the ground training. The ground training must include at least the following subjects:

If you (or anyone else) doubt that, ask the Chief Counsel, not AFS-800, because that's the only office whose opinion counts legally.

Please show us the Chief Counsel's ruling on it.

AFS-800 will not give you a signed memo on this because it's just his opinion, and carries no legal weight unless he's willing to put it into official form.

BTW, despite the title of 61.31(g), that paragraph applies to any "aircraft that has a service ceiling or maximum operating altitude, whichever is lower, above 25,000 feet MSL" whether pressurized or not -- read the definition in the first subparagraph (I've confirmed with AFS-800 that they really wanted it to read that way that way).

"That's the way they (AFS-800) wants it to read??" Since when was AFS-800 put in charge of writing the regulations??

 

[TMetzinger]

Strongly recommend the FAA physiological training (altitude chamber) given at OKC and at various military altitude chambers around the country. I took it at Langley in the '90s. You'll learn the basics and most importantly you'll learn your own reaction to hypoxia, which will likely be different than the person sitting next to you in the chamber. I get tingling in the hands and feet first. One person in our class just "went away" at FL250 with no changes they could detect.

I've have a couple of turbocharged airplanes (Mooney and Socata) at FL250. Wore a Scott demand mask that gave 100% O2 on inhalation. The issue was that it's REALLY cold up there in the fall and winter and the cabin heat was not very effective, which I assume was due to the decreased air density.

 

[Morne]

T337 has a service ceiling in the low 30's.

 

[tonycondon]

Pretty much every glider in the world is capabale of soaring over 25K and none of them currently are pressurized. One used to be (Lamson Alcor) and another is being built right now (Perlan)

 

[Jaybird180]

It's not stated plain language in the regulation. It's ambiguous at best.

(g) Additional training required for operating pressurized aircraft capable of operating at high altitudes.
(1) Except as provided in paragraph (g)(3) of this section,no person may act as pilot in command of a pressurized aircraft (an aircraft that has a service ceiling or maximum operating altitude, whichever is lower, above 25,000 feet MSL), unless that person has received and logged ground training from an authorized instructor and obtained an endorsement in the person's logbook or training record from an authorized instructor who certifies the person has satisfactorily accomplished the ground training. The ground training must include at least the following subjects:

I thought this section itself provided the definition of pressurized aircraft and that it had nothing to do with whether or not the cabin was airtight. So in this respect, I agree with the principle of what R&W is saying...they goofed when the wrote this section.

 

[Jaybird180]

Pretty much every glider in the world is capabale of soaring over 25K and none of them currently are pressurized. One used to be (Lamson Alcor) and another is being built right now (Perlan)

Is high-altitude psysiology covered in glider groundschool? Is it routine to carry O2 in a glider?

 

[flyingron]

The parenthetical statement DEFINES the term preceding. I agree with Ron, that the strict reading is not ambiguous. Now the only question is whether they actually intended to write it that way, and his inquiry shows that it is.

 

[flyingron]

Capable is not in that clause. I don't think gliders have service ceilings at all, and I'm not sure they have a maximum operating altitude defined in their limitations.

 

[tonycondon]

Is high-altitude psysiology covered in glider groundschool? Is it routine to carry O2 in a glider?

it is routine when you are flying in areas where you can expect to get well above 10K MSL. High altitude physiology is part of the training manuals, yes. The guys who are flying really high regularly in wave out west know their stuff.

 

[RotorAndWing]

The parenthetical statement DEFINES the term preceding. I agree with Ron, that the strict reading is not ambiguous. Now the only question is whether they actually intended to write it that way, and his inquiry shows that it is.

The fact of the matter is the department within the FAA (AFS-800) that can make the call on this won't do it is telling in itself. For that interpretation to carry any weight it needs to be on a FAA letterhead and signed by the Inspector making the assertion. Otherwise it's just opinion off the record.

 

[Alexb2000]

I can't think of a single pilot that had to get a high altitude endorsement for a non-pressurized piston. I've never seen it required in transition training, insurance, check rides, etc. If the rule is that you must have it for non-pressurized aircraft, then... a lot of people are not in compliance????

 

[dmspilot]

And are there any aircraft with a pressurization system that have a service ceiling or max operating altitude below 25,000? Would such an aircraft would require an endorsement?

 

[tonycondon]

i believe that some P210's were limited to 25K. probably to eliminate the need for the pilots to have a high altitude endorsement but also probably (more likely) because there are a lot more certification requirements when you fly above 25K

 

[gismo]

V35TC Bonanza and Cessna 401 are two.

That "death zone" is the issue. Above 25,000 MSL pressure altitude the time to serious physiological problems gets very short even when oxygen is provided to avoid hypoxia. The problem is that the ambient pressure is so low, that unless O2 is supplied under pressure, you can't get enough oxygen into the blood. See:

Ron, 100% O2 at ambient pressure will provide normal blood O2 saturation up to about 35,000 PA. This is obvious from simple physics (the partial pressure of O2 in air at 0 PA is equal to the pp of 100% O2 at approximately 37,000 PA). It's also shown in the paper you referenced which shows a blood O2 saturation of 95% at 35,000 PA on 100% O2 and indicates that pressure delivery is required above 40,000 PA (not 25,000 PA).

 

[N747JB]

i believe that some P210's were limited to 25K. probably to eliminate the need for the pilots to have a high altitude endorsement but also probably (more likely) because there are a lot more certification requirements when you fly above 25K

I think their pressurization system is fairly weak in comparison to other pressurized planes, particularly twin Cessnas. I think cabin altitude is 10,000 at 23,000 or so. It may actually be higher, I think the pressure differential is 3.2, maybe 3.5 psi? I took our old 414A RAM V, up to FL 290 once, once was enough, we just wanted to see if it would make the advertised speeds, it didn't. It was stable enough, but wallowed along in the thin air, I haven't had a twin Cessna over FL 230 again since 1995.

 

[gismo]

i believe that some P210's were limited to 25K. probably to eliminate the need for the pilots to have a high altitude endorsement but also probably (more likely) because there are a lot more certification requirements when you fly above 25K

AFaIK, the additional requirements for certification with a MOA greater than 25k only applies to pressurized airplanes. It appears that the requirements for a MOA above 25k involve designing the windshield to withstand the expected pressure when after any one structural component has failed.

Also worth noting is that any airplane certified under part 23 (vs CAR 3) must have a published MOA whether pressurized or not, but AFaIK no such requirement existed in CAR 3.

Finally I came across an obvious error in part 23 (hard to believe, eh?). Paragraph 23.1527(b) refers to 23.175(e) but it's pretty clear it should be pointed at 23.175(d).

 

[tonycondon]

i thought there were also some more stringent flutter requirements too above 25K. I vaguely recall reading an article that that is why the Cessnalumbia's were limited to 25K.

many gliders have a published Vne IAS vs altitude table. It goes down as you go up.

We used to take the 421 to FL250, on air sampling flights. I didn't really like the way it flew that high and it took so long to get up there that it would never really be worth it on a normal charter flight.

 

[Jaybird180]

The parenthetical statement DEFINES the term preceding. I agree with Ron, that the strict reading is not ambiguous. Now the only question is whether they actually intended to write it that way, and his inquiry shows that it is.

At the beauracracies I've worked for, getting it official is easier said than done.

 

[poadeleted20]

It's not stated plain language in the regulation. It's ambiguous at best.

(g) Additional training required for operating pressurized aircraft capable of operating at high altitudes.
(1) Except as provided in paragraph (g)(3) of this section, no person may act as pilot in command of a pressurized aircraft (an aircraft that has a service ceiling or maximum operating altitude, whichever is lower, above 25,000 feet MSL), unless that person has received and logged ground training from an authorized instructor and obtained an endorsement in the person's logbook or training record from an authorized instructor who certifies the person has satisfactorily accomplished the ground training. The ground training must include at least the following subjects:




Please show us the Chief Counsel's ruling on it.

AFS-800 will not give you a signed memo on this because it's just his opinion, and carries no legal weight unless he's willing to put it into official form.



"That's the way they (AFS-800) wants it to read??" Since when was AFS-800 put in charge of writing the regulations??

AFS-800 (810 to be exact) is and and has for a long time been in charge of writing Parts 61 and 141. Thus, they are the people who know better than anyone else what they intended the regulation to say. Beyond that, it's up to the Chief Counsel, and as I said, if you want to know what the Chief Counsel thinks the reg actually means (as opposed to what it was intended to mean), you'll have to ask them -- I only know what the people responsible for that reg wanted it to mean, and I've not said otherwise. And I really don't much care whether you believe me or not, but the definition of the term "pressurized aircraft" for the purposes of that section is right there in parentheses after the first use of the term -- and pressurization is not part of that definitions.

FWIW, I suggested to the folks there that if they really want it clearly understood what they meant without the sort of discussion we're having, they should change the word "pressurized" to "high altitude." Whether that happens or not remains to seen.

 

[poadeleted20]

The fact of the matter is the department within the FAA (AFS-800) that can make the call on this won't do it is telling in itself. For that interpretation to carry any weight it needs to be on a FAA letterhead and signed by the Inspector making the assertion. Otherwise it's just opinion off the record.

Nobody said this was a legal interpretation, just a statement of what the people who wrote the reg wanted it to mean. As I said, whether it actually means what they intended is a question for the Chief Counsel, and that so far is a question which has not been asked.

 

[poadeleted20]

I can't think of a single pilot that had to get a high altitude endorsement for a non-pressurized piston. I've never seen it required in transition training, insurance, check rides, etc. If the rule is that you must have it for non-pressurized aircraft, then... a lot of people are not in compliance????

I think you are correct, and that's a point I made in my discussion with the folks who own that reg.

 

[poadeleted20]

And are there any aircraft with a pressurization system that have a service ceiling or max operating altitude below 25,000? Would such an aircraft would require an endorsement?

There are quite a few, I think, with a limit of 25,000, and since the reg says "above," then the reg does not apply to them. I believe the Piper Malibu falls in that category.

 

[flyingcheesehead]

A turbo Twinkie is 30,000ft absolute ceiling I think

30K service ceiling on the turbo Twinkie.

Service ceiling is where the plane can only climb 100 fpm. Single-engine service ceiling on a twin is where the plane can only climb 50 fpm on one engine (FWIW, that's 19,000 on the turbo PA30B and 17,000 on the turbo PA30C/PA39).

Absolute ceiling is the highest the plane can possibly climb - And you'll only get there at one speed, somewhere between published Vx and Vy.

 

[gismo]

AFS-800 (810 to be exact) is and and has for a long time been in charge of writing Parts 61 and 141. Thus, they are the people who know better than anyone else what they intended the regulation to say. Beyond that, it's up to the Chief Counsel, and as I said, if you want to know what the Chief Counsel thinks the reg actually means (as opposed to what it was intended to mean), you'll have to ask them -- I only know what the people responsible for that reg wanted it to mean, and I've not said otherwise. And I really don't much care whether you believe me or not, but the definition of the term "pressurized aircraft" for the purposes of that section is right there in parentheses after the first use of the term -- and pressurization is not part of that definitions.

FWIW, I suggested to the folks there that if they really want it clearly understood what they meant without the sort of discussion we're having, they should change the word "pressurized" to "high altitude." Whether that happens or not remains to seen.

I'm puzzled why the service ceiling would be a qualifier here. The published service ceiling only applies at max gross weight in a standard atmosphere. Virtually any piston powered airplane with a service ceiling in the 20k range is capable of climbing above 25,000 when light on a cool day.

 

[RotorAndWing]

I'm puzzled why the service ceiling would be a qualifier here. The published service ceiling only applies at max gross weight in a standard atmosphere. Virtually any piston powered airplane with a service ceiling in the 20k range is capable of climbing above 25,000 when light on a cool day.

It has more to do with the caliber of people writing these regs. This is not the first time the whiz kids of DC have demonstrated they don't have a clue.

A little over 2 years ago these geniuses decided to rewrite the Rotorcraft Handbook. The new rewrite was given to a friend of mine working in -820 for a review. He said while it had really nice color graphics it became apparent the person in charge of the rewrite was not even rotorcraft rated (he confirmed it). The new handbook was so badly written it was sent back for another rewrite and just recently was approved. Even after approval there is an "errata sheet" published because of more bad information that was published in the manual.

Trying to uphold AFS-800 as the all seeing-all knowing "authorities" is laughable at best.

 

[dmspilot]

There are quite a few, I think, with a limit of 25,000, and since the reg says "above," then the reg does not apply to them. I believe the Piper Malibu falls in that category.

Ok, I think I agree on that, even though 61.31(g)(2) does not give an altitude.

that paragraph applies...whether pressurized or not

Really? If it doesn't matter if it's pressurized or not then why put the word "pressurized" a half dozen times?

(g) Additional training required for operating pressurized aircraft capable of operating at high altitudes. (1) Except as provided in paragraph (g)(3) of this section, no person may act as pilot in command of a pressurized aircraft (an aircraft that has a service ceiling or maximum operating altitude, whichever is lower, above 25,000 feet MSL), unless that person has received and logged ground training from an authorized instructor and obtained an endorsement in the person's logbook or training record from an authorized instructor who certifies the person has satisfactorily accomplished the ground training. The ground training must include at least the following subjects:
(i) High-altitude aerodynamics and meteorology;
(ii) Respiration;
(iii) Effects, symptoms, and causes of hypoxia and any other high-altitude sickness;
(iv) Duration of consciousness without supplemental oxygen;
(v) Effects of prolonged usage of supplemental oxygen;
(vi) Causes and effects of gas expansion and gas bubble formation;
(vii) Preventive measures for eliminating gas expansion, gas bubble formation, and high-altitude sickness;
(viii) Physical phenomena and incidents of decompression; and
(ix) Any other physiological aspects of high-altitude flight.
(2) Except as provided in paragraph (g)(3) of this section, no person may act as pilot in command of a pressurized aircraft unless that person has received and logged training from an authorized instructor in a pressurized aircraft, or in a flight simulator or flight training device that is representative of a pressurized aircraft, and obtained an endorsement in the person's logbook or training record from an authorized instructor who found the person proficient in the operation of a pressurized aircraft. The flight training must include at least the following subjects:
(i) Normal cruise flight operations while operating above 25,000 feet MSL;
(ii) Proper emergency procedures for simulated rapid decompression without actually depressurizing the aircraft; and
(iii) Emergency descent procedures.

 

[Jaybird180]

Now I'm scratching my head at the eerily argumentative agreement. I think I got what I came for.

Thanks Ron, R&W, et al.

 

[poadeleted20]

Really? If it doesn't matter if it's pressurized or not then why put the word "pressurized" a half dozen times?

I have no idea, but that's what they did, and that's what they said they wanted it to mean. Beyond that, you'll have to write to AGC-200.

 

[RotorAndWing]

I have no idea, but that's what they did, and that's what they said they wanted it to mean. Beyond that, you'll have to write to AGC-200.

If that were true they have avenues to fix it. The simplest avenue would be for AFS-800 to got to the Region Attorney and have him write the GC and request a ruling. The other would be for them to submit a rule change through the proper channels.