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Aviation Decision Making

Human Factors, Crew Health

Human factors is a combination of aviation medicine, psychology, engineering and ergonomics. It encompasses all of these factors trying to understand the man/machine interface in the aircraft. It has its roots in aviation accident investigations resolving these where no clear technical cause could be found when aircraft became more and more reliable over the years.

An airplane should be pre-flighted and determined safe to fly, but what about the pilot? Be aware that there are a number of medical conditions which could lead to the pilot be grounded, and here we take a look at some of them.

To withstand all demands of the flying environment the pilot must be qualified, fit and maintain a healthy life style for a clear body and mind. The pilot must also be aware when he or she is not fit or even fatigued or is using drugs to counter minor illnesses which could affect performance or even flight safety.

Fitness to Fly, I

Pilots who become incapacitated during flight are a real danger to the safety of passengers and the aircraft. The risk is much less with a multi-crew flight but if this happens during a bad weather night approach in a busy environment it could develop in an real emergency real fast. And for private pilots flying with passengers during low visibility conditions the danger is the same.

Medical examinations

Before an aspiring pilot may fly solo (and to keep exercising the privileges of the license) he/she must pass the required regular medical examinations for the license. There are several so called classes, with different requirements depending on the license. Commercial pilots usually must be able to pass the highest requirements and standards.

As can be expected, these examinations are designed to exclude those medical conditions not compatible with flying.

Heart disease

Coronary Artery Disease

Humans with a possible change on a heart condition as coronary artery disease, which is likely to cause chest pain and a heart attack or an infarct, must be detected in an early stage to make sure that this condition does not develop during flight, with possible fatal results.

The risk factors for a coronary artery disease are: family history, smoking, elevated blood pressure or cholesterol level due to inflammation of the arteries, lack of exercise, high blood sugar level, overweight and stress. All but family history can be managed with by living a healthy life, an adequate diet and regular exercise.

Eye health

Pilots (and most people) need good vision after correction with glasses, contact lenses and or eye surgery. The limits to be accepted for any class of medical regarding vision are more strict than when you already posses a medical license. It is best to contact your medical examiner should you have any issues or questions.

Color/ Night vision

Sensitivity Human Eyes

In human eyes, colors are detected by the cones (7 million) in the retina, these are most sensitive for wavelengths around 555 nm (green yellow), and are used in daylight. During low light conditions the rods (75 to 150 million) are used and these are sensitive around 500 nm and play little role in color vision. The eyes are not linearly sensitive for colors, we therefore need more red and blue (compared to green/yellow) to see colors in the dark. Streetlights are orange/yellow for this reason. See: www.radiantvisionsystems.com/blog/language-light for more info. Image sourced from Radiant Vision Systems.

The colors used for flying (or seeing) in the dark should be selected such that the eyes are not desensitized by the brightness of the light source. Red lights seems to be best, but then some of the colors on your map will be unreadable. Nowadays multi-color led flashlights are affordable enough and can solve this problem by using green and red together.

Blood glucose

The human body needs energy to function and this gets into the system through food. The level of glucose is regulated by the pancreas, which secretes insulin into the blood stream to keep the amount of glucose at normal levels. Problems can arise if the pancreas delivers too much (low blood sugar, hypoglycemia) or the body has become resistant to insulin (diabetes type 2) or even does not produce enough (diabetes type 1).

Low blood glucose levels can also occur by not eating enough (think of missing meals or not drinking enough) and this can cause fainting, shakiness, nervousness and or cold sweating. Prolonged high blood sugar levels (combined with high insulin) can cause kidney failure, blindness, promote cancer and heart attacks if not treated properly. Those who develop diabetes are likely to have some trouble keeping their license.

For pilots it is important to eat and drink to keep their blood glucose at normal levels. Listen to your body: eat when hungry and stop eating when nourished. You can have a small sandwich with a mixed filling just in case and drinking enough fluids should prevent low blood glucose levels and keep the pilot fit to fly. Make sure to keep the amount of carbohydrates to less than 75 grams per day (LowCarbHighFat).


For more information see the next links to the FAA Safety Brochures and EASA Aircrew & Medical websites. These contain all the details you may wish to know about being a pilot and having possible limiting medical conditions.

Written by EAI.

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