Federal Aviation Administration - Glider Flying Handbook

. A human-powered ornithopter is virtually incapable of flight due to the dramatic difference in the strength-to-weight ratio of birds compared to humans.

Aeronautical decision making (ADM) is a systematic approach to the mental process used by pilots to consistently determine the best course of action in response to a given set of circumstances. The importance of learning effective ADM skills cannot be overemphasized. While progress is continually being made in the advancement of pilot training methods, aircraft equipment and systems, and services for pilots, accidents still occur. Despite all the changes in technology to improve flight safety, one factor remains the samethe human factor. It is estimated that 65 percent of the total glider accidents are human factors related. Historically, the term pilot error has been used to describe the causes of these accidents. Pilot error means that an action or decision made by the pilot was the cause of, or a contributing factor that lead to, the accident. This definition also includes the pilots failure to make a decision or take action. From a broader perspective, the phrase human factors related more aptly describes these accidents since it is usually not a single decision that leads to an accident, but a chain of events triggered by a number of factors.

The poor judgment chain, sometimes referred to as the error chain, is a term used to describe this concept of contributing factors in a human factors related accident. Breaking one link in the chain normally is all that is necessary to change the outcome of the sequence of events. The following is an example of the type of scenario illustrating the poor judgment chain.

An experienced glider pilot returning from a cross-country flight is approaching a jagged mountain ridge that lies between him and his home airport located in the valley below. As he nears the ridge he sees people on the top waving to him in excitement. Overjoyed with having flown over 400 kilometers, he decides to do a low pass over the peak. He is flying into a 30 knot headwind that is blowing across the peak. Holding what he feels is adequate airspeed as he nears the lee side of the peak, he realizes his altitude is not very high in relation to the peak of the ridge. As he nears the peak he finds himself in a strong downdraft created by the strong wind blowing over the ridge. In an attempt to make a 180 turn to avoid contacting the ridge, the pilot puts his glider into a steep right turn and pulls back hard on the control stick resulting in an accelerated stall/spin. In the ensuing crash, the pilot is fatally injured and the glider is completely destroyed.

By discussing the events that led to this accident, we can understand how a series of judgmental errors contributed to the final outcome of this flight. For example, one of the first elements that affected the pilots flight was his inability to realize that his decision-making skills were probably dulled by the long distance flight, which preceded the accident. The pilot had flown over this ridge a number of times and was aware that downdrafts are often present on the lee side of the peak but had never had problems in the past.