Abstract. The modern problems of low-altitude aircraft radio altimeters is researched and a new diagnostic method is proposed to solve existing problems in this article. It is shown that controlling the correct operation of the radio altimeter system can be carry out based on the use of a new diagnostic method. As a result, it is possible to take measures to eliminate false readings of the system on board and thereby to ensure flight safety by increasing the reliability of information received from the radio altimeter system. The main advantages of the proposed diagnostic method are that it can be carried out both in flight and in ground service, and also can be applied without contact in radio altimeter system of the aircraft.

Keywords: Flight Safety, correct operation, radio altimeter system, modern problems, autonomous diagnostic method.