Spatial Disorientation (SD) has been a causal factor in aviation accidents since its inception. Exhaustive studies have been conducted to identify the causes of this condition in manned aircraft, and train crew members to recognize, confirm, and recover from its potentially deadly onset. SD in UAS however has not been extensively studied due to the fact that human beings are remotely operating the aircraft and because of that were not subjected to the classic conditions associated with SD. For this discussion, answer the following questions:
What are the different types of SD and how can they occur in UAS? Does SD affect an UAS crew member differently than in a manned aircraft? What SD mechanisms specific to UAS can be identified? What can be done to prevent SD in UAS? Are there any GCS modifications that could be made to lessen the likelihood of SD occurring?
There are several different forms of illusions that can create spatial disorientation in aircraft as well as UAS. Spatial orientation is our natural ability to maintain our body orientation and/or posture in relation to the surrounding environment at rest and during motion (FAA, n.d.). In FAA studies as a result of aircraft accidents the FAA has concluded that between 5% -10% of all general aviation (GA) accidents can be attributed to spatial disorientation of which 90% are fatal (FAA, n.d.). The 2 main types of common illusions that are associated with flight; somotogravic and somatogyral (Jedik, 2013). Somatogravic occurs during acceleration and deceleration that can create a sensation of climbing and descending (Jedik, 2013). Inside the ground control station you would be less susceptible to such sensation as a result of being still and you are not experiencing linear acceleration or deceleration as one experiences in a traditional aircraft. Somatogyral illusions during straight and level flight can create situations such as the leans where a pilot has a false sense of the horizon or have a sense of turning in the opposite direction (Jedik, 2013). Personally, I have not seen these types of illusions in unmanned aircraft like I have in traditional manned platforms.
The aerial perceptive illusions are prevalent in UAS, especially the systems that I work with, that create issues when landing especially looking through the soda straw. For example, on final approach to the runway at Dugway Proving Ground one may experience an illusion as a result of the extremely long runway (was an alternate for the space shuttle) and may create the illusion of being too high. This can create a tendency to push the stick forward to get down the landing surface creating a situation that could result of nosing the aircraft into the runway. A final approach to an unusually wide runway may give the impression of being lower than actual (FAA, n.d.). This could result in the pilot pitching the aircraft at low speed resulting in a stall and possible accident. A final approach over flat terrain that has an upsloping runway may result in the illusion that one is conducting a high altitude final (FAA, n.d.). Correcting this could result pitching the aircraft down and cause an accident. Conversely, a final over flat terrain with a downsloping runway could produce the illusion of a low-altitude final. If one believes this illusion the resulting in pitching nose up to gain altitude with possibly a low power setting and airspeed resulting in a stall. One way to help mitigate such illusion is to trust the instrumentation and spend time working on these issues in a simulator. Another way to combat this type of disorientation is to trust in the right seater and ask questions about the approach especially if you feel like you could be experiencing such a situation.
References
Federal Aviation Administration. (n.d.). Spatial disorientation: visual illusions. Retrieved from www.faa.gov/pilots/safety/pilotsafetybrochures/media/spatiald.pdf (Links to an external site.)
Jedik, R. (2013). Spatial disorientation. http://goflightmedicine.com/spatial-disorientation/ (Links to an external site.)