Abstract: An indirect aiming measurement method based on reference conversion was developed for the aircraft without aiming window. By installing a reference conversion device at the tail of the aircraft,the attitude information of the aircraft inertial measurement unit and the reference conversion device are collected in the horizontal and vertical states,and the vertical state is aimed at the prism of the reference conversion device through the ground strapdown on the laser strapdown inertial unit to obtain the northward azimuth angle of the prism,and the initial azimuth angle of the aircraft inertial measurement unit is obtained through matrix conversion and other calculations,so as to realize the aiming measurement of the aircraft. 

Key words: Reference conversion, Aiming measurement