Updated: Dec 30, 2020

Hypoxia can creep up on pilots and cause very dangerous situations. It is important to know the causes of Hypoxia and its symptoms.

Here's what you need to know.


Hypoxia means "reduced oxygen" or "not enough oxygen." Although any tissue will die if deprived of oxygen long enough, the great threat to pilots is its effects on mental functions while flying.


There are 4 types of hypoxia (or causing sources), what are they?

Hypoxic Hypoxia

Is a result of insufficient oxygen available to the body as a whole. The most common cause of this in the aviation industry is the partial pressure of oxygen at higher altitudes. Essentially, at higher altitudes, the oxygen molecules are spread further apart. This can result in the body being unable to inhale enough oxygen to maintain certain mental functions.

Hypemic Hypoxia

Is a result of the body's blood cells not being able to take up and transport oxygen molecules to the brain. The most common cause of Hypemic Hypoxia, while flying, is CO (Carbon Monoxide) poisoning. This is because CO can attach itself to blood cells 200 times faster than oxygen. This means, the blood cells will be transporting CO to the brain instead of the necessary oxygen molecules.

Stagnant Hypoxia

Is a result of the blood not flowing to the brain. While there may be enough oxygen in the environment, and that oxygen is attaching to the body's blood cells, there may still be symptoms of Hypoxia if the blood is not flowing to the brain to deliver those oxygen molecules. In flying, this is most commonly found while pulling excessive accelerations of gravity (G-Forces). During G-Forces, blood may pool in the lower extremities of the body, preventing it from flowing to the brain.

Histotoxic Hypoxia

Is the result of the brain rejecting oxygen molecules that are being delivered by the body's blood cells. This can be caused by drugs and alcohol. It is important to avoid alcohol and certain prescription drugs when preparing or performing flight operations.


Cyanosis (blue fingernails and lips)


Decreased Response Times

Impaired Judgement


Visual Impairment


Dizzy Sensations


Tingling in the Fingers and Toes


Descend to a Lower Altitude

Put on an Aviation Approved Oxygen Mask

Stop Pulling G-Forces

Author - Nate Hodell

CFI/CFII/MEI/ATP - Creator of wifiCFI - Owner of Axiom Aviation Flight School.

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