Abstract: The motion law in approach for carrier aircraft was analyzed by applying Doppler shift. When carrier aircraft is in uniform glide motion, the proportional navigation guidance law can be derived according to the condition that Doppler changing rate tends towards zero. Then, the retarded motion at equal proportion is emphatically researched and the conclusion is obtained that adjacent Doppler changing rate tends to equal. Based on the fact that the approach for carrier aircraft must be practically a retarded motion, this paper presented an engineering solution detecting glide angle and velocity of carrier aircraft in mobile platform. As opposed to the available multistation measurement mode, the analytic equation of velocity vector of carrier aircraft from Doppler shift equation can be directly derived making use of angle transformation introduced by directionfinding although the location parameter is unknown. The analog calculation verifies that the derived formula of velocity vector is errorless. The error analysis shows that the measuring error of velocity vector is less than 0.1 m/s if the rms value of measurement error of the velocity for aircraft carrier is less than 0.1 m/s.

Key words: approach and landing, guidance law, speed measurement, Doppler positioning, active location system