This paper is devoted to the assessment of professionally important qualities of aviation engineering and technical personnel, as well as their impact on the safety and regularity of flights. Detailed analysis of the causes, conditions and circumstances, that cause human errors, and the development of methods and means for their prevention. A list of basic professionally important qualities of aviation technical personnel, which can be used during the training of specialists, hiring, appointment, etc. has been developed. The proposals for the improvement of processes of formation of professionally important qualities of aviation maintenance personnel in their training and future career in the airlines have been developed.