[Problems of flight safety and effectiveness of aviation specialists' activities]

In all cases reliability of aviation specialists' activities is a parameter influenced by complex of intrinsic and extrinsic matters. That proves the concept of absolutely safe flights to be inadequate, necessitates justification of the maximal safety level providing the reliability degree which is potentially available. The actual risk always exceeds the expected one, and the difference between them shows the resources and approaches to optimize aviation systems through more reliable specialists and equipment. Flight accidents have three groups of causes traced to human factor. The first group comprises social factors and peculiarities of pilots' and aviation supervisors' training. This group is in charge of nearly 50% of the accidents. The second group includes ergonomic drawbacks of the equipment and induces 25% of flight accidents. The third group covers medical and psychologic factors which show not only the pilot's health, but the functional resources tending to decrease during the activities. This group also causes about 25% of the accidents. If higher expenses for training of pilot causing the accident risk equal to 0.01, amount of flight accidents could decrease several times, and overall expenses will be optimal (nearly 2 times lower than now).