Simulation Sickness


The human body has many ways to react to unusual situations which are designed to either warn us of danger, encourage us to get away from the dangerous situation or remove a poison from our body. For example, the sense of vertigo most people experience at heights is a tell tale sign that your body thinks you are too high off the ground and you could fall and cause yourself harm. So your brain makes you feel unwell untill you get back down to ground level again, where you feel better again.
Unfortunately even though you are placed in a Flight Simulator, your body will still suffer the effects of motion sickness to varying degrees. However there are degrees of susceptibility to be aware of and ways to minimise the effects when you head off to your next simulator ride.

Defining Motion Sickness

Kinetosis or Motion Sickness as it is commonly refered to, is "a condition in which a disagreement exists between visually perceived movement and the vestibular system's sense of movement". You may have experienced this yourself whilst travelling in a car, boat or aircraft in the form of nausea, sweating, headaches or a sense of vertigo. Did you know the same effect is present in the training environment as well?


The Thales FLight Simulator in action (image embedded from Wikipedia on 14 August 2012)

Simulation Sickness

Modern Full motion Flight Simulators of today provide a high fidelity experience with large potential for positive transfer of learning. But as with a lot of things in Aviation, the Human element can demonstrate primitive traits which are a potential area of concern; with some individuals suffering motion sickness whilst in the Flight Simulation environment.

The most common theory for the cause of simulation sickness is that the illusion of motion created by the virtual world, combined with the incorrect sense or even absence of motion detected by the inner ear, causing the area postrema in the human brain to infer that one is hallucinating and further conclude that the hallucination is due to poison ingestion. The brain responds by inducing nausea and mass vomiting, to clear the supposed toxin.
The symptoms are often described as quite similar to that of motion sickness, and can range from headache, drowsiness, nausea, dizziness, vomiting and sweating.

Problems resulting from Simulator Exposure

  • three quarters of those expose tend to experience levels of Nausea, disorientation and oculomotor problems, with about 1.5 % actually vomiting. Rates of Simulator Sickness increase at about 23% per 15min concurrent exposure time and prolonged effects of sickness can be expected following exposure with symptoms lasting more than 24 hours.
  • Females appear to be more susceptible to motion sickness and experience higher levels of oculomotor and disorienting symptoms than males.
  • Individuals exposed to simulator sessions can be expected to experience drowsiness and fatigue following exposure.
  • Flashbacks which involve visual illusion of movement or false sensations of movement can be expected to occur following exposure to a Simulator.

What factors determine the level of Simulation Sickness?

  • Individual capacity (susceptibility)
  • Amount of Time exposed
  • Stimulus intensity

Ways in which the effect can be minimised
The Individual is best advised to treat the Simulator session as they would if they were going flying. Ensure that they are prepared, have had adequate rest, not under influence of drugs or alcohol, not suffering cold or flu symptoms. The key area here is rest from not only the last Simulator exposure, but flying actual aircraft. In some people a reverse effect occurs which after a Simulator session they then become airsick in the aircraft, not an ideal situation.
Although not within their control, age and gender appear to be factors. Females in general are more susceptible and both Males and Females over 25 years old are half as susceptible as when they were 18 years old. There is also very limited data which suggests that here does become a point where older (unspecified data) people become more susceptable again to the various stresses involved.
But above all, the main factor in determining individual susceptibility appears to be prior levels of Simulator experience, where over time the body becomes accustomed to the various stresses involved.

Simulator Session initally avoid rapid and rotational moments, start with short exposures and build up the session times. If possible it is recommended that an intersession interval of 2-5 days is maintained to reduce Simulator Stimulus levels. Complex visual scenes are more nauseogenic than simple scenes; this is exacerbated by a large field of view, high spatial frequency content and visual simulation of action motion. Other technical areas to watch for are: visual to motion lags and ensuring that multimodal feedback is provided which minimises sensory conflicts (visual, aural, kinaesthetic).

1. Hancock, P. A, Mouloua, M, Vinvenzi, D. A, Wise, J. A (2009). Human Factors in Simulation and Training, Boca Raton, USA: CRC Press
2. Motion Sickness Retrieved from Wikipedia on 13/08/2012. [].

Want to know more?

Motion Sickness
Wikipedia has a general page on Kinetosis
Vestibulo-Ocular Reflex
Another Wikipedia page describing in-depth how the eye stabilises itself

Contributors to this page


Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License