Spatial disorientation
Encyclopedia
Spatial disorientation is the inability to correctly interpret aircraft attitude, altitude or airspeed, in relation to the Earth or point of reference. Spatial disorientation is a condition in which an aircraft
pilot
's perception of direction (proprioception
) does not agree with reality. While it can be brought on by disturbances or disease within the vestibular system
, it is more typically a temporary condition resulting from flight into poor weather conditions with low or no visibility. Under these conditions the pilot may be deprived of an external visual horizon, which is critical to maintaining a correct sense of up and down while flying.
A pilot who enters such conditions will quickly lose spatial orientation if there has been no training in flying with reference to instruments
. Approximately 80% of the private pilots in the United States
do not have an instrument rating
, and therefore are prohibited from flying in conditions where instrument skills are required. Not all pilots abide by this rule, and approximately 40% of the NTSB fatal general aviation accident reports list continuation of flight into conditions for which the pilot was not qualified as a cause.
caused by turning, the net gravitoinertial force sensed primarily by the otolith organs is not aligned with gravity, leading to perceptual misjudgment of the vertical. In addition, the inner ear contains rotational "accelerometer
s," known as the semicircular canals, which provide information to the lower brain on rotational accelerations in the pitch, roll and yaw axes
. However, prolonged rotation (beyond 15-20 s) results in a cessation of semicircular output, and cessation of rotation thereafter can even result in the perception of motion in the opposite direction. Under ideal visual conditions the above illusions are unlikely to be perceived, but at night or in weather the visual inputs are no longer capable of overriding these illusory nonvisual sensations. In many cases, illusory visual inputs such as a sloping cloud deck can also lead to misjudgments of the vertical and of speed and distance or even combine with the nonvisual ones to produce an even more powerful illusion. The result of these various visual and nonvisual illusions is spatial disorientation.
The graveyard spiral usually terminates when the g-force
s on the aircraft build up to and exceed the structural strength of the airframe
, resulting in catastrophic failure, or when the aircraft contacts the ground. In a 1954 study, the Air Safety Foundation
found that out of 20 non-instrument-rated subject pilots, 19 of the 20 entered a graveyard spiral soon after entering simulated instrument conditions. The 20th pilot also lost control of his aircraft, but in another maneuver. The average time between onset of instrument conditions and loss of control was 178 seconds.
Spatial disorientation can also affect instrument-rated
pilots in certain conditions. A powerful tumbling sensation (vertigo
) can be set up if the pilot moves his head too much during instrument flight. This is called the Coriolis illusion
. Pilots are also susceptible to spatial disorientation during night flight over featureless terrain.
Good spatial orientation on the ground relies on the use of visual, vestibular (organs of equilibrium located in the inner ear), and proprioceptive (receptors located in the skin, muscles, tendons, and joints) sensory information. Changes in linear acceleration, angular acceleration, and gravity are detected by the vestibular system and the proprioceptive receptors, and then compared in the brain with visual information.
Spatial orientation in flight is difficult to achieve because numerous sensory stimuli (visual, vestibular, and proprioceptive) vary in magnitude, direction, and frequency. Any differences or discrepancies between visual, vestibular, and proprioceptive sensory inputs result in a sensory mismatch that can produce illusions and lead to spatial disorientation.
, so the pilot may not realize that the aircraft is accelerating, decelerating, or banking.
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
pilot
Aviator
An aviator is a person who flies an aircraft. The first recorded use of the term was in 1887, as a variation of 'aviation', from the Latin avis , coined in 1863 by G. de la Landelle in Aviation Ou Navigation Aérienne...
's perception of direction (proprioception
Proprioception
Proprioception , from Latin proprius, meaning "one's own" and perception, is the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement...
) does not agree with reality. While it can be brought on by disturbances or disease within the vestibular system
Vestibular system
The vestibular system, which contributes to balance in most mammals and to the sense of spatial orientation, is the sensory system that provides the leading contribution about movement and sense of balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of...
, it is more typically a temporary condition resulting from flight into poor weather conditions with low or no visibility. Under these conditions the pilot may be deprived of an external visual horizon, which is critical to maintaining a correct sense of up and down while flying.
A pilot who enters such conditions will quickly lose spatial orientation if there has been no training in flying with reference to instruments
Instrument flight rules
Instrument flight rules are one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other are visual flight rules ....
. Approximately 80% of the private pilots in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
do not have an instrument rating
Instrument rating
Instrument rating refers to the qualifications that a pilot must have in order to fly under IFR . It requires additional training and instruction beyond what is required for a Private Pilot certificate or Commercial Pilot certificate, including rules and procedures specific to instrument flying,...
, and therefore are prohibited from flying in conditions where instrument skills are required. Not all pilots abide by this rule, and approximately 40% of the NTSB fatal general aviation accident reports list continuation of flight into conditions for which the pilot was not qualified as a cause.
Senses during flight
During the abnormal acceleratory environment of flight, the vestibular and proprioceptive systems do not respond vertically. Because of inertial forces created by acceleration of the aircraft along with centrifugal forceCentrifugal force
Centrifugal force can generally be any force directed outward relative to some origin. More particularly, in classical mechanics, the centrifugal force is an outward force which arises when describing the motion of objects in a rotating reference frame...
caused by turning, the net gravitoinertial force sensed primarily by the otolith organs is not aligned with gravity, leading to perceptual misjudgment of the vertical. In addition, the inner ear contains rotational "accelerometer
Accelerometer
An accelerometer is a device that measures proper acceleration, also called the four-acceleration. This is not necessarily the same as the coordinate acceleration , but is rather the type of acceleration associated with the phenomenon of weight experienced by a test mass that resides in the frame...
s," known as the semicircular canals, which provide information to the lower brain on rotational accelerations in the pitch, roll and yaw axes
Flight dynamics
Flight dynamics is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw .Aerospace engineers develop control systems for...
. However, prolonged rotation (beyond 15-20 s) results in a cessation of semicircular output, and cessation of rotation thereafter can even result in the perception of motion in the opposite direction. Under ideal visual conditions the above illusions are unlikely to be perceived, but at night or in weather the visual inputs are no longer capable of overriding these illusory nonvisual sensations. In many cases, illusory visual inputs such as a sloping cloud deck can also lead to misjudgments of the vertical and of speed and distance or even combine with the nonvisual ones to produce an even more powerful illusion. The result of these various visual and nonvisual illusions is spatial disorientation.
Effects of disorientation
Once an aircraft enters conditions under which the pilot cannot see a distinct visual horizon, the drift in the inner ear continues uncorrected. Errors in the perceived rate of turn about any axis can build up at a rate of 0.2 to 0.3 degrees per second. If the pilot is not proficient in the use of gyroscopic flight instruments, these errors will build up to a point that control of the aircraft is lost, usually in a steep, diving turn known as a graveyard spiral. During the entire time, leading up to and well into the maneuver the pilot remains unaware that he is turning, believing that he is maintaining straight flight.The graveyard spiral usually terminates when the g-force
G-force
The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...
s on the aircraft build up to and exceed the structural strength of the airframe
Airframe
The airframe of an aircraft is its mechanical structure. It is typically considered to include fuselage, wings and undercarriage and exclude the propulsion system...
, resulting in catastrophic failure, or when the aircraft contacts the ground. In a 1954 study, the Air Safety Foundation
Air safety
Air safety is a term encompassing the theory, investigation and categorization of flight failures, and the prevention of such failures through regulation, education and training. It can also be applied in the context of campaigns that inform the public as to the safety of air travel.-United...
found that out of 20 non-instrument-rated subject pilots, 19 of the 20 entered a graveyard spiral soon after entering simulated instrument conditions. The 20th pilot also lost control of his aircraft, but in another maneuver. The average time between onset of instrument conditions and loss of control was 178 seconds.
Spatial disorientation can also affect instrument-rated
Instrument flight rules
Instrument flight rules are one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other are visual flight rules ....
pilots in certain conditions. A powerful tumbling sensation (vertigo
Vertigo (medical)
Vertigo is a type of dizziness, where there is a feeling of motion when one is stationary. The symptoms are due to a dysfunction of the vestibular system in the inner ear...
) can be set up if the pilot moves his head too much during instrument flight. This is called the Coriolis illusion
Sensory Illusions in Aviation
Because human senses are adapted for use on the ground, navigating by sensory input alone during flight can be dangerous: sensory input does not always accurately reflect the movement of the aircraft, causing sensory illusions. These illusions can be extremely dangerous for pilots.-Vestibular...
. Pilots are also susceptible to spatial disorientation during night flight over featureless terrain.
Spatial Orientation
Spatial orientation is our ability to maintain our body orientation and/or posture in relation to the surrounding environment (physical space) at rest and during motion. Humans have evolved to maintain spatial orientation on the ground. The three-dimensional environment of flight is unfamiliar to the human body, creating sensory conflicts and illusions that make spatial orientation difficult and sometimes impossible to achieve. Statistics show that between 5% and 10% of all general aviation accidents can be attributed to spatial disorientation, 90% of which are fatal.Good spatial orientation on the ground relies on the use of visual, vestibular (organs of equilibrium located in the inner ear), and proprioceptive (receptors located in the skin, muscles, tendons, and joints) sensory information. Changes in linear acceleration, angular acceleration, and gravity are detected by the vestibular system and the proprioceptive receptors, and then compared in the brain with visual information.
Spatial orientation in flight is difficult to achieve because numerous sensory stimuli (visual, vestibular, and proprioceptive) vary in magnitude, direction, and frequency. Any differences or discrepancies between visual, vestibular, and proprioceptive sensory inputs result in a sensory mismatch that can produce illusions and lead to spatial disorientation.
The Otolith Organs and Orientation
Two otolith organs, the saccule and utricle, are located in each ear and are set at right angles to each other. The utricle detects changes in linear acceleration in the horizontal plane, while the saccule detects gravity changes in the vertical plane. However, the inertial forces resulting from linear accelerations cannot be distinguished from the force of gravity (according to the theory of general relativity they are the same thing) therefore, gravity can also produce stimulation of the utricle and saccule. A response of this type will occur during a vertical take-off in a helicopter or following the sudden opening of a parachute after a free fall."Seat of the pants" flying
Anyone in an aircraft that is making a coordinated turn, no matter how steep, will have little or no sensation of being tilted in the air unless the horizon is visible. Similarly, it is possible to gradually climb or descend without a noticeable change in pressure against the seat. In some aircraft, it is possible to execute a loop without pulling negative G so that without visual reference, the pilot could be upside down without being aware of it. That's because a gradual change in any direction of movement may not be strong enough to activate the fluid in the vestibular systemVestibular system
The vestibular system, which contributes to balance in most mammals and to the sense of spatial orientation, is the sensory system that provides the leading contribution about movement and sense of balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of...
, so the pilot may not realize that the aircraft is accelerating, decelerating, or banking.
In the media
- The Day the Music DiedThe Day the Music DiedOn February 3, 1959, a small-plane crash near Clear Lake, Iowa, killed three American rock and roll pioneers: Buddy Holly, Ritchie Valens, and J. P. "The Big Bopper" Richardson, as well as the pilot, Roger Peterson. The day was later called The Day the Music Died by Don McLean, in his song...
- Feb 3, 1959 - This phenomenon was extensively reported in the press in 1999, after John F. Kennedy, Jr.John F. Kennedy, Jr.John Fitzgerald Kennedy, Jr. , often referred to as John F. Kennedy, Jr., JFK Jr., John Jr. or John-John, was an American socialite, magazine publisher, lawyer, and pilot. The elder son of U.S. President John F...
's plane went downJohn F. Kennedy, Jr. airplane crashOn July 16, 1999, John F. Kennedy, Jr. died when the Piper Saratoga light aircraft he was piloting crashed into the Atlantic Ocean off the coast of Martha's Vineyard, Massachusetts. His wife, Carolyn Bessette, and sister-in-law, Lauren Bessette, were also killed. His flight departed from Essex...
during a nightNightNight or nighttime is the period of time when the sun is below the horizon. This occurs after dusk. The opposite of night is day...
flight over water near Martha's VineyardMartha's VineyardMartha's Vineyard is an island located south of Cape Cod in Massachusetts, known for being an affluent summer colony....
. Subsequent investigation pointed to spatial disorientation as a probable cause of the accident. - It is believed that world-famous singer, Jim ReevesJim ReevesJames Travis Reeves , better known as Jim Reeves, was an American country and popular music singer-songwriter. With records charting from the 1950s to the 1980s, he became well-known for being a practitioner of the Nashville sound...
, was suffering from spatial disorientation when his Beechcraft aircraft crashed in the Brentwood area of Nashville, Tennessee during a violent thunderstorm on Friday 31st July 1964, claiming the lives of both Reeves and his pianist Dean Manuel. - Intentionally-induced spatial disorientation (by use of giant mirrors) was a major plot point in the two-part TaleSpinTaleSpinTaleSpin is a half-hour American animated television series based in the fictional city of Cape Suzette, that first aired in 1990 as part of The Disney Afternoon, with characters adapted from Disney's 1967 animated feature The Jungle Book. The name of the show is a play on "tailspin", the rapid,...
episode, "A Bad Reflection on You."
See also
- Aeroperú Flight 603AeroPeru Flight 603Aeroperú Flight 603 was a scheduled flight from Jorge Chávez International Airport in Lima, Peru , to Comodoro Arturo Merino Benítez International Airport in Santiago, Chile , which crashed on October 2, 1996....
- Agni Air Flight 101Agni Air Flight 101Agni Air Flight 101 was a regional flight operated by Agni Air between Kathmandu, Nepal and Lukla, Nepal that crashed on 24 August 2010, killing all 14 people on board. 20 minutes after take-off from Kathmandu, the flight crew had reported technical issues with the aircraft, and requested a return...
- August 24, 2010 - Air India Flight 855Air India Flight 855Air India Flight 855 was a scheduled passenger flight that crashed during the evening of 1 January 1978 about off the coast of Bandra, Bombay , India. All 213 lives on board were lost...
- January 1, 1978 - Atlasjet Flight 4203Atlasjet Flight 4203Atlasjet Flight 4203 was a scheduled flight from Istanbul's Atatürk International Airport to Isparta Süleyman Demirel Airport in Isparta, Turkey. On November 30, 2007 it crashed outside the town of Keçiborlu, 18 km from Isparta at around 01:36 EET...
- November 30, 2007 - Bárány chairBarany chairThe Barany chair or Bárány chair, named for the Austro-Hungarian physiologist Robert Bárány, is a device used for aerospace physiology training, particularly for student pilots. The subject is placed in the chair, blindfolded, then spun about the vertical axis while keeping his head upright or...
- Birgenair Flight 301Birgenair Flight 301Birgenair Flight 301 was a flight chartered by Turkish-managed Birgenair partner Alas Nacionales from Puerto Plata in the Dominican Republic to Frankfurt, Germany via Gander, Canada and Berlin, Germany...
- Brownout (aviation)Brownout (aviation)In aviation, a brownout is an in-flight visibility restriction due to dust or sand in the air.In a brownout, the pilot cannot see nearby objects which provide the outside visual references necessary to control the aircraft near the ground. This can cause spatial disorientation and loss of...
- The Day the Music DiedThe Day the Music DiedOn February 3, 1959, a small-plane crash near Clear Lake, Iowa, killed three American rock and roll pioneers: Buddy Holly, Ritchie Valens, and J. P. "The Big Bopper" Richardson, as well as the pilot, Roger Peterson. The day was later called The Day the Music Died by Don McLean, in his song...
- February 3, 1959 - Flash Airlines Flight 604Flash Airlines flight 604Flash Airlines Flight 604 was a charter flight operated by Egyptian charter company Flash Airlines. On 3 January 2004, the Boeing 737-300 crashed into the Red Sea shortly after takeoff from Sharm el-Sheikh International Airport, killing all 142 passengers, many of them French tourists, and all six...
- John F. Kennedy, Jr. - July 16, 1999
- Pilot errorPilot errorPilot error is a term used to describe the cause of an accident involving an airworthy aircraft where the pilot is considered to be principally or partially responsible...
- Jim ReevesJim ReevesJames Travis Reeves , better known as Jim Reeves, was an American country and popular music singer-songwriter. With records charting from the 1950s to the 1980s, he became well-known for being a practitioner of the Nashville sound...
- 31st July 1964 - Rocky MarcianoRocky MarcianoRocky Marciano , born Rocco Francis Marchegiano, was an American boxer and the heavyweight champion of the world from September 23, 1952, to April 27, 1956. Marciano is the only champion to hold the heavyweight title and go undefeated throughout his career. Marciano defended his title six times...
- Sensory illusions in aviationSensory Illusions in AviationBecause human senses are adapted for use on the ground, navigating by sensory input alone during flight can be dangerous: sensory input does not always accurately reflect the movement of the aircraft, causing sensory illusions. These illusions can be extremely dangerous for pilots.-Vestibular...
External links
Information from the following government documents is in the public domain.- http://www.cami.jccbi.gov/AAM-400A/Brochures/spatialD2/spatialD2_home.htm
- http://www.cami.jccbi.gov/AAM-400A/Brochures/DISORIEN.HTM
- http://www.cami.jccbi.gov/AAM-400A/Brochures/SpatialD.htm
- http://www.cami.jccbi.gov/AAM-400A/Brochures/SpadialD_page2.htm