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Night Flight And Hypoxia

Sat Jun 12, 2004 3:11 am

I know that the effects of hypoxia can be felt at much lower altitudes during flight at night. I was wondering why. I know that the AIM recomends using supplemental oxygen above 5000 feet at night.

If you have any insite or details, I'd really appreaciate it.

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RE: Night Flight And Hypoxia

Sat Jun 12, 2004 3:17 am

Interesting question, I thought that lack of oxygen just made your nightvision worse, I would be very surprised if the effects are more noticable just because it's dark.

Altitude is Insurance - Get Insured
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RE: Night Flight And Hypoxia

Sat Jun 12, 2004 3:21 am

I have also read all of the things about hypoxia in the AIM, and I think they are a bit exagerrated. I am in good physical condition and don't smoke, so I should last a little longer and get more oxygen than someone not like me, but I have never experienced shortness of breath, headaches, lightheadedness, loss of color in vision, blurred vision, or anything else while flying above 10,000' in a light airplane. I have gone up to 13,000' in both night and day. I 5 hour night flight at 11,000' would be a different story, of course, especially for someone who lives at sea level. Maybe that would warrant bringing and using oxygen, or cruising at a lower altitude.

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RE: Night Flight And Hypoxia

Sat Jun 12, 2004 3:59 am

In NM we pretty much ignore that rule and fly up to around 10,000 at night, seeing as were already 5000 feet ASL.
Holy sh*ts and burritos.
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RE: Night Flight And Hypoxia

Sat Jun 12, 2004 4:25 am

When I was going through the altitude chamber, part of the training is to show you how bad you're night vision can be affected. They take you up to the equivalent of about 7000ft. (can't recall for sure the exact altitude) The whole time you're looking at a color wheel, after a few minutes they have you put on your mask and go to 100% oxygen. Man, how those colors became so much more vibrant and jumped up at you.
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RE: Night Flight And Hypoxia

Sat Jun 12, 2004 4:35 am

I'm pretty sure its only your night vision that is affected worse at altitude during night flight. I believe the rods require more oxygen to be effective.

All in all I would adhere to and maybe even go beyond the FARs on oxygen use in general. My DE for my PPL check ride had a couple scary stories of people who were within the reg's, but got hypoxia, kept blowing off check points, and ended up flying the plane right into the ground. The problem tends to compound itself as you become euphoric and don't think there'e anything wrong with you.

5000 feet ASL

??? Hybrid of MSL/AGL?