Understanding disorientation and the human frailties that contribute to this seductive siren are essential to a pilot’s longevity. God graced us with legs to travel the earth’s surface. He did not fit us with wings for good reason.
Three senses interact to keep us upright, feet firmly planted on terra firma - vision (eyes), proprioception (“seat of the pants”, pressure sensing organs in the skin and joints), and vestibular (balance apparatus in the inner ear called the semicircular canals). Blindness is a disability but not incapacitating as the remaining two senses compensate with the aid of touch and hearing.
Once airborne the rules change dramatically with the two fallible senses, proprioception and vestibular being negated. Vision rules supreme as the only reliable orientation sense once the aircraft abandons the earth’s surface. Remove the natural horizon, ignore attitude instruments and your lifespan is reduced to an average of three terror filled minutes!
There are certain natural phenomena and emergency situations which may deprive a pilot of his/her vision. The brilliance of the low setting sun can temporarily blind a pilot as he/she flares to land. A windscreen covered with ice or oil from a failed engine can severely restrict visibility. Smoke in the cockpit from a combusting bird’s nest or an oil starved engine can have serious consequences. On one occasion a combination of sweat and suntan lotion led to my temporary visual loss while taking off a Super Cub on floats from Powell Lake. I was fortunate to stagger into the air without digging a float or striking surface debris. Had I been unsuccessful, accident investigators would never have deduced the cause of the accident A direct bird strike on the windscreen can result in catastrophic visual impairment with plexiglass fragments, blood and feathers. Chick Childerhose in his book “Wild Blue” recounts Syd Burrows’ encounter with a bird while flying a Sabre jet. He was awarded the Air Force Cross for getting this aircraft back to base despite serious orbital trauma. To date I have not heard of an accident resulting from inadvertent release of bear spray in the cockpit of a floatplane or helicopter. Hopefully wise cargo storage will prevent such a disaster. Vision and aircraft control go hand in hand.
Pilots should be aware that spatial disorientation can be one of three distinct types - each just as seductive and deadly.