The brochure addresses technical safety issues; main factors affecting flight safety; the concept of methods of quantitative assessment of flight safety is given. The main attention is paid to the set of works necessary to create aviation equipment with high reliability and ensure it during operation, as well as various methods for establishing the causes of prerequisites for flight accidents and their prevention. The brochure is intended for the flight and engineering personnel of the aviation of the Armed Forces, the Ministry of Civil Aviation, DOSAAF, students, cadets and students of technical and flight educational institutions.