In this article, I'll give you some information about the causes and consequences of spatial disorientation. This will probably not help you with flying your flight simulator aircraft, but it's a very interesting subject -- especially if you're into general aviation and VFR flights.

// What is spatial disorientation?

The reason we can maintain our equilibrium while walking (or riding a bicycle) and sense changes in our body orientation is simple: the brain receives sensory information from various receptors -- mainly eyes and ears -- to detect acceleration and therefore sense balance. The changes in acceleration (pitch, yaw and roll) are percepted by the vestibular system (inner ears) and compared in the brain with visual information. On the ground, the information sensed by the vestibular system and the vision usually match, so we have a good spatial orientation. You can temporarily disturb your sense of balance by closing your eyes and turning rapidly in circles five or six times. The fluid in your ears will start to move and it will take a few seconds for the liquid to lose momentum, and until then the sense from your inner ear conflicts with the information coming from your vision, causing dizziness and disorientation. When the information coming from the vestibular system and the vision do not match, we have a condition called spatial disorientation.

This condition is more frequent in flight, and typically occurs when a non-instrument rated pilot attempts to fly in low visibility or at night. Flying without a defined external horizon can be very dangerous, since we are missing a good visual reference -- the brain will rely solely on the information provided by the vestibular system, which may not be accurate. The pilot who attempts to fly an aircraft based only on his vestibular system's output might end up putting the aircraft in an abnormal attitude -- and he won't want that for sure! For example: in a zero-visibility situation, a pilot who rapidly increases thrust will have the sensation of being climbing and a pilot who rapidly decreases thrust will have the sensation of being descending. If the pilot senses a climb when the aircraft is actually levelled, he might miscorrect the attitude by starting a real descent -- in low heights, that might result in a crash.

In a study made by the Air Safety Foundation, which selected 20 non-instrument rated pilots to enter a simulator where a low visibility scenario was loaded, it was concluded that 100% of the pilots lost control of the aircraft. The average time between onset of instrument conditions and loss of control was 178 seconds. Shocking, isn't it?!

// That sounds serious. How can I avoid spatial disorientation?

The solution is simple, very simple: trust the instruments. Trust the attitude indicator; trust the turn coordinator; trust the vertical speed indicator. They don't suffer from spatial disorientation and are very accurate. If the attitude indicator shows a bank angle of 10 degrees but it kinda feels like you're flying straight and level, you are indeed banked 10 degrees! Additionally, if one is not a fully qualified instrument pilot, it's also a good practice to never fly without a defined external horizon, in reduced visibility or at night. With the advent of the GPS technology, many (non-instrument) pilots are forgetting this simple rule, but avoiding adverse weather is fundamental to flight safety.

This is the first article published at FS Station. We will frequenty publish other articles concerning interesting aviation topics. Send your article suggestions to bernardosrulzon[at]fsstation.com !