Icarus, the prisoner that dared to touch the heavens; his story of flight captivated humanity with the dream of flight for centuries. With the coming of the first powered and controlled flight in 1903 by the Wright brothers, to fifth-generation fighter aircraft, this ancient dream became reality. Yet, as Icarus ignored his father’s warnings and fell from the sky, modern pilots too can be deceived, not by the sun, but by their own senses.
But how does this deception happen?
Flight & Spatial Disorientation
Unlike birds who have been flying for around 150 million years, the human body has evolved to move on solid ground, meaning in a two-dimensional space. Not through a three-dimensional space where one can experience differing flight maneuvers, or acceleration at multiple gravitational forces (G-force), that make orientation difficult to maintain. Naval Pilots rely not only on their flight instruments, but also their visual, and vestibular senses to navigate in the skies. Any variation in these senses causes spatial disorientation (SD); which according to a study done in 2014, 20% of all plane accidents are related to the pilot’s optical illusions. There are three classifications to SD:
Type 1: Unrecognized
- These SD’s are unrecognized by the pilot.
Type 2: Recognized
- The Pilot recognizes the SD, and can attempt to correct it.
Type 3: Incapacitating
- The pilot is incapacitated and cannot save himself nor recover the aircraft
The Lying Senses
Within the inner ear lies the vestibular system acting as our built-in balance sensor, and gyroscope; with its main goal being that we are oriented upright, straight, and level. There’s two parts to the vestibular system: the semicircular canals that detect angular/rotational movement, and the otolith organs that detect linear acceleration. But, like any man-made sensor, it has limits. The vestibular system is sensitive to G-force, and prolonged maneuvers, creating illusions that fall into two categories: somatogyral for spinning illusions, and somatogravic, for acceleration illusions.
Imagine you’re flying through the clouds in an F-35C, no visible terrain, and the horizon is obstructed. You bank into a turn, the fluid in your semicircular canals start moving, but after a while your brain no longer recognizes that you’re still in a bank as the fluid in your ear has reached equilibrium within the canal wall. Then you exit the clouds and level out, your eyes and instruments may say your level, but the fluid in your inner ear is still moving, giving pilots the urge to bank the aircraft into an attitude to correct this feeling; a situation called “the leans,” a somatogyral illusion.
Vision isn’t the savior
During flight, vision is the most important sense needed not just for flying, but to achieve accurate spatial orientation. But, vision can betray you in the sky. Your eyes and brain work together in order to decipher how light reflects off things, this “vision” allows pilots to see their surroundings and help navigate through the skies. However, if a pilot is in an maneuver where their exposed to high G-Forces, they can be “G-Locked,” or have an G-induced loss of consciousness that can negatively effect their vision as it constricts blood flow to the brain causing pilots to lose sharpness in their vision. 3-4 G’s is whenever a pilot without adequate G-force protection can expect gray vision (blurred central vision), with the pilot blacking out between 5-7 G’s.
Bringing it Home
Aerospace technology is only continuing to get better, and the understanding of the human physiology, and the biomechanics of Spatial Disorientation remain a constant. Pilots must not only learn to master their aircraft, whether it be for a commercial purpose to protect the lives of the passengers, or a military purpose to fulfill the mission, but they must also understand their own biology as well. This understanding of the human body’s limitation is the only way to prevent and counteract spatial disorientation. After all, as Icarus learned long ago, the sky may be beautiful, but it is not forgiving.
Featured Image from USN
Further Reading:
