The leans

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The Leans is the most common type of spatial disorientation among pilots . By stabilizing the fluid in the semicircular canals of the organ of equilibrium, a pilot can perceive a straight and level flight, while in reality the aircraft is in a curve. This is caused by a quick return to level flight after a gradual, lengthy turn that the pilot was not aware of. The phenomenon consists of a false perception of the angular displacement around the roll axis and therefore becomes the illusion of the curve. This illusion is often associated with a vestibulospinal reflex, which causes the pilot to actually lean towards the misperceived vertical. Other common explanations for the Leans phenomenon are deficiencies in both the otolith organ and sensory mechanisms of the semicircular canals.

physiology

The Leans is a kind of vestibular illusion in flight that causes spatial disorientation. The process involves the semicircular canals of the vestibular system . The semicircular canals recognize angular accelerations. There are three semicircular channels in total: the front, back, and side channels. Each canal is filled with a fluid called an endolymph , and each canal is made up of a small sac-like structure called an utricle . At the ends of each channel is a bag-like part called an ampoule. Inside are hair cells and supporting cells known as the crista ampullaris.

When you change a person's orientation, certain channels are stimulated through these hair cells. When the head rotates, the ducts move, but because of its sluggishness, the endolymphatic fluid tends to lag, thereby stimulating the hair cells. This stimulation leads to an awareness of angular acceleration in this plane. After about 10 seconds, the endolymph velocity equals that of the duct, which stops stimulating the hair cells and reduces the person's rotational awareness. In addition, the channels cannot detect rotational acceleration of about 2 degrees per second or less; this is the stimulus threshold of the semicircular canals. As a result, a pilot may not notice a slow turn or hold a turn long enough. After the pilot flattens the wings, there is the illusion that the aircraft is banking too much in the opposite direction. In response, the pilot often leans toward the original turn in an attempt to correct and regain his / her perception of the correct vertical position. The leans can also be caused by peripheral visual cues that are misleading.

Dangers and Risk

If a pilot does not notice the disorientation and continues to lean, the aircraft can bank in the wrong direction and cause taxiing. This is the most common spatial disorientation for pilots. In all cases of spatial orientation, pilots must be able to rely on their flight instruments for control in order to overrule false sensory perceptions.

See also

Individual evidence

  1. ↑ Jeffrey Davis: Fundamentals of Aerospace Medicine . LIPPINCOTT WILLIAMS & WILKINS, Philadelphia 2008, pp. 180-181.
  2. ↑ Kenneth S. Saladin: Anatomy & Physiology: the unity of form and function . 6th edition. McGraw-Hill, New York 2012, ISBN 978-0-07-337825-1 (English).
  3. ^ A b Roger Shaw: Spatial Disorientation: Trust Your Instruments . Retrieved June 25, 2018.
  4. ^ Spatial Disorientation: Confusion that Kills . In: Safety Advisor for Air Safety . AOPA Air Safety Foundation. Retrieved June 25, 2018.