Abstract. Metrological reliability, which is a characteristic of the quality of measurement systems, determines their ability to maintain metrological characteristics over time within the established standards during operation in specified modes and conditions of use, maintenance, storage and transportation. Consequently, metrological reliability is determined by the nature and rate of change in the normalized metrological characteristics of measurement systems. The development of methods for assessing and improving the metrological reliability of aviation instruments at the design stage, taking into account the temperature conditions of operation, is an urgent task, the solution of which will make it possible to introduce the required level of metrological reliability into the technical requirements for the design of aircraft instruments and achieve it already during their design, evaluate metrological reliability indicators at arbitrary times operating time, recommend the duration of calibration intervals and the timing of preventive maintenance, take measures to prevent metrological failures, and in general, improve the quality of the designed aviation instruments.