AN/GSN-5 mobile automatic landing system is a low approach and landing aid for modern aviation, providing capabilities for ground controlled talk-down approach, automatic or pilot-coupled low approach, and fully automatic landing for aircraft having suitable autopilots. Precise-tracking conical-scanning radar determines aircraft position and transfers data to computer which selects desired glide slope, glide angle, and determines altitude command as a function of range to touch-down. Alternate methods of transmission provided by GSN-5A - ILS and radar beam coding-are described. The beacon and decoder provide a system combining high tracking accuracy with a high capacity private data link.