In the continuing theme of compensation versus adaptation, we will look at some of the ‘hard wired’ protective mechanisms found in humans. These are automatic responses that are designed to protect the body from harm. For example, our hands jerk back automatically when heated excessively, so we don’t burn ourselves. We close our eyes when the light becomes too bright. For the most part such action has no positive or negative application to flying. However some of our protections that are quite useful on the ground can have negative consequences in the flying environment.
For instance, when the blood rushes towards our head we feel that we are falling headfirst. Normally on the ground the only way to get this effect is to actually fall. Our natural instinct in these cases is to push our hands out to protect our head. In the air however this effect is easy to produce, even when we are sitting upright. We should not be surprised how strong these reactions are as children do them without training or first hand experience. When driving in a car most people feel discomfort when driving over a bump. Mild 'sub-gravity' sensations can be viewed as a bit of excitement or can produce more extreme reactions. This reaction of moving our hands to protect our heads can be very inappropriate when flying aircraft. The most serious cases in flight training result in students trying to avoid all movement in the direction the aircraft is going. This can result in jamming the stick forward and turning the head away.
A related protective mechanism is invoked when objects appear to rush towards us. Our hardwired reaction is to move our hands out in front of us and our head to the side, to protect our head and eyes. This is readily demonstrated if you watch kids playing with a water fountain or a hose with water spurting towards their heads. Again this response to the ground apparently rushing upwards may not be correct for pilots with their hands on the control column. The last thing we want them to do at this point is to move the control column forward and turn their heads away.
Some special care must be taken when teaching stall or spin recovery to help our intellect take over. It is important to get students to remain centred in the aircraft, and follow it’s motion, rather than to try to escape it. If these feelings are not overcome, the protective reaction in a three-dimensional environment will only serve to heighten sensations and make things worse.
We don’t even have to go that far with our visual sensations. When humans perceive an edge, they almost immediately feel like leaning away. This effect is also enhanced if there is any associated falling sensation. In flight, the effect is to lean away from the direction of the turn. This leads to problems in accurately perceiving the qualities of the turn, and further exaggerates the feeling of excessive bank. Again students must be urged to stay centred in the aircraft both to promote accuracy in their control and to decrease the effect of these sensations. Again, most of these protective mechanisms must be unlearned in the flying environment. It often takes a lot of conscious effort to make sense of what is felt and seen, and come up with the appropriate responses.