Abstract: The operating compatibility between air intake and engine during the flighttests of a supersonic fighter is considered. The flight tests were completed under conditions of huri zontal accelerating flight, uprated and retarded throttles of the engine during horizontal flight and constant-Mach climbing with maximum and augmented thrust rating. The flow conditions at the intake and the tendency of flowfield variation at the inlet of the engine were evaluated by means of six prossure tappings at the variable intake cone and a cross rake pressure probe at the exit of the intake. The technical measures have been taken to cope with the engine troubles and their effects are also described in the paper.