Two experimental glide-path controllers have been designed for the Cornet lllB aircraft, using a parametric optimisation procedure. Their theoretical performance in the presence of all known disturbances is discussed in detail and compared with that of a controller currently in use with this aircraft. Both controllers show considerable theoretical improvements in beam holding, particularly with respect to turbulence, in which an improvement of 5:1 in the rms height error and 2:1 in the rms velocity error is attained at the end of the approach. Further improvement in performance is known to be restricted by the limitations of the Cornet power control equipment.