Welcome Guest. Sign in or Signup

6 Answers

Night Flying Oxygen Real ?

Asked by: 13639 views FAA Regulations

I understand the rules about usage of supplemental oxygen being required for the minimum crew above 12.500-1400 in excess of 30 minutes, and between 14.000-15.000 the entire crew is required to use supplemental oxygen and above 15.000 everyone must use it assuming were flying during the day that the sun is out heating the surfaces which heats up the air next to it. Why is it that during night flying supplemental oxygen is required above 5000ft when the air should be cooler/denser and easier to breathe since the sun is not out? Please explain to me where im going wrong here :/ 

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

6 Answers

  1. Best Answer


    Aaron on Oct 01, 2014

    I think you’re confusing the AIM recommendation with a regulation. Oxygen is not REQUIRED at 5000 feet at night, it is recommended by the AIM. Here in Denver, we don’t fly all our night flights on O2… the recommendation doesn’t have anything to do with the heating of the earth. It had to do with the FAA deeming night flying more hazardous and weight of extra precautions. The FAA recommends oxygen above 5000 at night because it will help keep those pilots from suffering any effects of hypoxia, especially those aviators echo are not acclimated to the altitude (I.e. those who fly at sea level). Think of how some people are susceptible to “altitude sickness” (hypoxia) when they come to cities like Denver and you’ll understand the motivation behind this recommendation.

    -1 Votes Thumb up 0 Votes Thumb down 1 Votes



  2. Koehn on Oct 01, 2014

    The recommendation for supplemental oxygen above 5,000′ at night has to do with the effects of even relatively mild hypoxia on night vision. The eye’s night vision degrades far more rapidly with lower levels of oxygen than does its day vision. The increased density due to cooler temperatures at night doesn’t overcome the far lower density due to altitude.

    +3 Votes Thumb up 3 Votes Thumb down 0 Votes



  3. victor torres on Oct 01, 2014

    Thanks Aaron I was also reading that during night flight the eyes need to secrete a certain protein in order to give adequate vision, and like you said night flying is already hazardous so they recommend the use of oxygen to not only reduce symptoms of hypoxia but alleviate the eyes as well. By the way out in Denver when do you use O2 ?

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  4. Aaron on Oct 02, 2014

    As Kohen said, vision- particularly night vision is one of the first senses to be diminished in effectiveness in the early obey of hypoxia. Personally I’ve never used oxygen, but I’ve also not been operating aircraft above altitudes where oxygen was required. It’s kind of funny to me, we spend significant amounts of time above 12, 13, 14,000 feet skiing and hiking and such. Weird for me to think that when I’m up in the mountains, I’d need oxygen had I been at the same spot flying a plane. That said as I alluded to earlier, I see the (sometimes severe) acclimation issues some people have when they head to the high country, and so I completely understand and respect the importance of compliance with oxygen regulations.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  5. Brent on Oct 02, 2014

    For the record, 91.211 requires that each occupant be provided with oxygen, not that they must use it.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  6. Brent on Oct 02, 2014

    Specifically, I’m referring to the 91.211(a)(3) requirement relating to cabin pressures at or above 15,000′.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes


Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.