A false sense of movement, causing disorientation and confusion is known as Vertigo. This state of our mind can ultimately lead to incapacitate.
According to a data from FAA, vertigo and spatial disorientation (SD) is the reason for nearly 15% of accidents, particularly in instrument meteorological conditions (IMC) or during night time.
It is something that can also happen to experienced pilots and most are fatal.
633 crashes were investigated by the US Air Force and 13% of them were due to SD. Surrounded by SD, the life expectancy of a non-instrument-rated pilot is less than 3 minutes in IMC.
We receive feedback from our feedback based on the inputs received from nerve receptors, proper functioning of inner ear, and a combination of gravitational and visual inputs.
A big role in inducing vertigo is played by our inner ear. Ever induced a “dead arm” from from lying on it? You have no idea of its whereabouts except for looking at it blankly.
The inner part of our ears has three semicircular canals where changes takes place when the aircraft pitch, roll or yaw. Movement is sensed by specialized cells and fluid in these canals and the information is sent to our brain.
You can understand confusion created when you are sitting in a stationary train and the train besides you start moving. Most of simulators at theme park play with these senses and you are made to believe that you are upside down.
When a pilot experiences Vertigo / SD initially there is a conflict between instruments and sensations. The disconnection blurs out things and it ultimately leads to incapacitation followed by muscle spasms, visual disturbances, nausea and panic.
Different flying maneuvers lead to specific and compelling types of disorientation. This emergency is different from others like engine failure or cockpit fire, as the disoriented pilot lives with the perception that everything is right.
The problem starts when the aircraft spiral after a bank, which gives the feeling that nose has dropped. Most pilots respond by pulling back on yoke to reduce the thought rate of descent or initiate a climb.
The problem is magnified when the aircraft enters a stall, with too much stress on aircraft structure or it flies to the ground.
Due to a sudden transition, the pilot feels that he or she is turning in the opposite direction. Attempt is made to correct the perceived orientation and the aircraft is turned back to the original bank.
In case the pilot third his head in a direction opposite to airplane’s rotation at the time of making a turn, it may give a feeling of rolling sensation. An erroneous inputs of roll, yaw, or pitch may occur depending on orientation.
After a high-performance climb, the pilot may get the illusion that he is inverted. As the aircraft level off, the pilot feels lightness in seat and it instructs the pilot to increase the pitch more, which may lead to further feeling of inversion.
There are many problems that can lead to vertigo and deserves medical attention. Sudden head movements may result in benign paroxysmal positional vertigo (BPPV) and it may be recurrent, transitory or incapacitating.
This may be due to infection in inner ear or loss of hearing. Meniere disease may occur abruptly associated with tinnitus (having a ringing sound in ears) and this can be long lasting.
Abnormal movements of eye may also happen. There are some medical conditions which look like vertigo, multiple sclerosis being one of them.
Migraine, head trauma, acoustic nerve tumors, insufficient blood supply to the brain and diabetes may also cause similar symptoms.
A pilot has to get his or her medical history checked and undergo thorough medical examination to know about the root cause of the problem. To suppress symptoms, a pilot may be recommended Sermont or Epley exercises by the physician.
Different home remedies are also there but they lack scientific evidence on efficacy.
Vertigo symptoms can be controlled by several medications however, FAA has not approved any of them.
A pilot has to make sure that he or she does not suffer from vertigo before acting as PIC. Interestingly, diphenhydramine which is one of the medicine often prescribed for vertigo, has been the reason for many fatal accidents.
Anti-infective medicines or steroids may have a role to play.
May be, in future, pilots suffering from spatial disorientation may be assisted by technology such as Automatic Ground Collision Avoidance System (A-GCAS).
A last word of advice is that we should not fly if we are taking any medication or had insufficient sleep the night before or very tired.