A dual I.L.S. glide slope system for allowing a normal 3.degree. descent path plus an additional 6.degree. descent path which can be used for noise abatement procedures etc. In accordance with the present invention these glide slopes are provided on a single assigned R.F. channel with no inverted courses interposed. The first signal null will occur at 9.degree. elevation when all signals will be zero, producing a "flag" alarm.
A guidance system for landing an aircraft is described which uses a source of signals identifiable with the aircraft and a ground station which is linked to the aircraft. Specifically, the ground station includes a receiver which is connected to one or more pairs of antennas having a fixed, overlapping, directional sensitive pattern symmetically located relative to the center of the landing path, a receiver and a processor for measuring the relative sensitivity of the signals received at the antennas and for using the relative signal intensity to determine the location of the aircraft relative to the center of the landing path.
