Glideslope

A portion of an Instrument Landing System (ILS). The glide slope is a radio beam extending upward at angle of approximately 21 from the approach end of an instrument runway. The glide slope provides the vertical path for the aircraft to follow when making an ILS approach along the localizer path. The horizontal needle of the cross-pointer indicator (the ILS indicator) shows the pilot the relative position of the aircraft as it descends along the glide slope. The glide slope is sometimes called the glide path.