Altitude, Oxygen and Non-Pressurized "Safe Routes" Charts

[Calvin Waterbury]

I did some research on the altitude it would be safe to carry non-pilot passengers. I was surprised to hear that altitude sickness can occur at any altitude over 8,000 feet if allowed enough time to develop. Some of what I read said the FAA has set a hard and fast rule that pilots have to get on oxygen when crossing 10K, but that is only for pilots. I don't know of any regs for passengers. I do know someone who flys RW at 11,500 for hours at a time and there has never been any issues AFAIK.

The reason I am asking is I have set up a small private VA for my family members, "Yellow Rose Airways VA" to provide some focus and reason to fly. I need to set up routes and establish preferred altitudes for various aircraft, including pressurized and non-pressurized airplanes. So, I have two questions...

(1) Based on your own experience in RW flight, what altitude is the safest altitude to fly passengers in non-pressurized aircraft?

(2) Assuming the above is standardized somewhere, is there an FAA chart/sectional which only shows non-pressurized (no Oxygen) "safe routes" on the chart/sectional?

[Keith Smith]

The FAA rules state that if the cabin altitude is between 12,500 and 14,000, then oxygen is required for crew members after 30 minutes.

If between 14,000 and 15,000, crew require oxygen immediately.

If > 15,000, oxygen must be made available to everyone.

Where did you see a rule that mentioned 10,000ft?

The only charts that exist are the ones that you're familiar with, low/hi-enroute, area charts, WAC charts, fly charts, TAC charts and sectionals. None of them reference anything to do with oxygen.

[Keith Smith]

Regarding the 'safest' altitude for passengers, the only worthwhile reference I can give you is that the cabin altitude on most airliners is around 8000ft once you get to altitude. So, if you're going to go much above that, it would be more than what most passengers have probably experienced in their lives, unless they're mountain climbers or skiers.

I have spent prolonged periods at 11,500 and am very happy at that altitude. 12,000 is ok. 13,500 is something I've experienced for 22 minute stretches, and it wasn't pleasant, started getting slight headache and slightly spacey before calling it a day. Felt noticeably better after coming down to 12,000 after that.

A pulse oximeter would probably be a useful tool as it allows you to objectively measure the blood oxygen levels of you and your passengers if you were doing this for real. As a simulated exercise, the FAA says you're good below 12,500.

[Calvin Waterbury]

...
Where did you see a rule that mentioned 10,000ft?

I have to plead senility... I don't remember.

The only charts that exist are the ones that you're familiar with, low/hi-enroute, area charts, WAC charts, fly charts, TAC charts and sectionals. None of them reference anything to do with oxygen.

That answers my question. Thanks!

[Calvin Waterbury]

Regarding the 'safest' altitude for passengers, the only worthwhile reference I can give you is that the cabin altitude on most airliners is around 8000ft once you get to altitude. So, if you're going to go much above that, it would be more than what most passengers have probably experienced in their lives, unless they're mountain climbers or skiers.
...

Aha! There's a telling bit of kit! According to this, the *safest* limit for non-pressurized aircraft would be 8K. Ok, that will probably be the standard to adopt for YRA for non-pressurized birds. This is good from another perspective. Since my children are working on there SPCs and/or PPLs in the real world, adopting and enforcing a 8,000 foot limit in their sim flying would make and keep them aware of it.

Thanks for the help!

[Pieces]

I believe the 10,000 ft oxygen number comes from commercial ops (part 135): http://www.ecfr.gov/cgi-bin/text-idx?c= ... 18&idno=14

[Orest Skrypuch]

Most other jurisdictions requre O2 to all on board, if >30 min at 10000, and immediately at 13000 and above. I never fly above 10k without O2, and don O2 at 8k at night, but I have O2 readily available, I typically cruise 12k/13k.

Personally I think the FAA is too lax in this regard for Part 91 ops. Some folks will do just fine in the low teens, but it is not predictable as to who, without testing. A mini-pulse oximeter on board is a prudent step, they are quite cheap now. I check every 30 mins or so, or whenever I think about it. You do not want to be below 90 %sat, I will control the O2 to achieve 93 -95.

If the passengers are boisterous, you can set them lower.

* Orest

[Calvin Waterbury]

@ Reece - Thanks for that link. Direct and to the point!

...
Personally I think the FAA is too lax in this regard for Part 91 ops.
...
* Orest

I could not agree more. As I read some crash and incursion commentary as well as general comments on the subject, I was surprised to find this area was relatively lax on FAA's part, especially in light of how strict the regs are in many other areas of less importance. What could be more important than this basic physiology. One non-aviation organization put it like this...

"When you can't breathe, nothing else matters."

Food for thought.

[Keith Smith]

I didn't realize the Part 135 regs were different, very good to know. I recalled there was a lot of material regarding the proximity of oxygen masks in the flight levels, but didn't know it was different below 12,500 than Part 91.

It's important for pilots to experience higher cabin altitudes with an instructor to recognize the signs. For example, on my mountain flying checkout (which we weren't able to complete) in Norcal, we were up at 11,500. I was having a great time...a really great time. The fluffy clouds looked soooo awesome (you see where this is going, right?). "I'm feeling a little hypoxic, how about you?" asks the instructor, "me? Feeling great!"

We continued flying above them as they became more and more developed below us (scattered, broken and eventually overcast). "ohhhhh. Maybe....we should turn around?" "Great idea." said the instructor..."you should've made that call more than 10 miles ago. Tune the xxx VOR and let's get out of here."

I then spent the next 30 seconds wondering why I couldn't dial the VOR into what turned out to be the COM1 radio.

"What on earth is wrong with me?"

"You're hypoxic."

*crickets*

"ohhhhhhhh."

From that day on, once I'm above 10k or so, I generally give myself math and ADM problems to contend with every few minutes (gas, fuel, time, distance...whatever) to make sure I'm not staring at the pretty clouds and getting fuzzy.

[Daddy O]

Kieth, is your plane pressurized?