In general term, vertigo could mean dizziness, unsteadiness or lightheadedness. This term has been commonly used in medical field as a major symptom of balance disorder. From its etymology, vertigo comes from the Latin "vertere" which means to turn and -igo which is a condition of turning about. Although vertigo could mean differently in different professions, vertigo or spatial disorientation, in the aviation world, is a condition wherein which an aircraft pilot's sense of direction contradicts or does not agree with reality. It is a condition wherein which the sufferer is unable to determine the true position of the body. Based from my readings, according to its most widely used definition, one that has been accepted by a large number of countries, Spatial Disorientation (SD) refers to the pilot's: "… [failure] to sense correctly the position, motion or attitude of his aircraft or of him/herself within the fixed coordinate system provided by the surface of the earth and the gravitational vertical". Spatial Disorientation is different from geographic disorientation as the latter is the loss of awareness of location in relation to a particular place in the Earth's surface.
By nature, human beings are able to maintain Spatial orientation on ground. It is our natural ability to maintain our body's orientation and/or posture in relation to the surrounding environment (physical space) at rest and during motion. However, the flight environment is unfamiliar to the human body under normal circumstances. It can be harsh and tricky and it creates sensory conflicts and illusions that make spatial orientation difficult, and, in some cases, even impossible to achieve. This is where Spatial Disorientation takes place.
While vertigo can literally mean dizziness, it is the human's failure to picture the position relative to the horizon that makes it a truly dangerous problem. This is basically the reason why spatial disorientation is one of the major concerns and issues in the aviation world. Further to my readings, "statistics show that between 5% and 10% of all general aviation accidents can be attributed to spatial disorientation, 90% of which are fatal." (ref. AV8ER ON OCTOBER 4, 2009)
Moreso, Spatial Disorientation has been considered a phenomenon and is one of the significant hazards in the industry. In fact, several major accidents involving pilot's spatial disorientation in large commercial airlines have caused attention to the international aviation safety community.
Some flight incidents/reports concerning Spatial Disorientation
- This phenomenon was extensively reported in the press in 1999, after John F. Kennedy, Jr.'s plane went down during a night flight over water near Martha's Vineyard. Subsequent investigation pointed to spatial disorientation as a probable cause of the accident.
- It is believed that world-famous singer, Jim Reeves, 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.
- An accident near Nassenwil/Zurich, Switzerland on 10 January 2000, about 1756 local time, Crossair Flight 498, a Saab 340B carrying three crewmembers, seven passengers, took off from Unique Zurich Airport (ZRH), Switzerland in night instrument meteorological conditions.
- Accident on 23 August 2000 about 1930 local time, Gulf Air Flight 72, an Airbus A320 carrying eight crewmembers and 135 passengers crashed into the Arabian Gulf near Muharraq, Bahrain in dark night visual meteorological conditions.
- On 3 January 2004, about 0445, Flash Airlines Flight 604, a Boeing 737-300 carrying six crewmembers and 142 passengers, crashed after departing Sharm el-Sheikh International Airport (SSH) in a dark night visual meteorological condition.
(Accident reports based from the case studies of William J. Bramble, Jr. Of the US National Transportation Safety Board on his case studies and countermeasures on Spatial Disorientation in Large Commercial Airplanes)
Reason behind spatial disorientation (vertigo)
Clinical/medical explanation of the phenomenon lies with the inner ear in the human body. Its functions are to give the brain information about rotation, altitude and linear motion of the head. It uses complex mechanism of canals and organs of equilibrium. Also, "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."
This is the reason why spatial orientation is hard to achieve in flight because of these numerous sensory stimuli responsible for our normal body's state. Also these stimuli vary in magnitude, direction and frequency. Any disagreements and conflicts between these stimuli will result in confusion and sensory mismatch that can produce illusions and eventually lead to spatial disorientation. Not having a good visual of the outside can add up to the feeling of confusion and disillusion leading to SD.
Prevention of spatial disorientation (vertigo)
- knowing the problem and understanding its causes, prevention and possible treatment
- in conditions of low or zero visibility and weather, do not rely on VFR but on IFR
- getting Instrument Rating training should be done
- if flying by yourself you might try to regain your orientation by quickly closing your eyes and tilting your head left and right, you still have to consider relying on your instruments
- if you feel disorientated, when flying a multi-crew aircraft, hand over the control to the other pilot
- always prepare well for your flight – study the geographical specificities and weather conditions of the region of your flight
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