A component of the Instrument Landing System (ILS) that provides the pilot with a vertical guidance for a precise descent angle to the runway.
See Glide Path.
The speed at which an aircraft is actually moving over the earth’s surface. A vector addition of True Airspeed and the wind component at its current altitude results in the velocity of the aircraft. The velocity is a vector quantity, the norm (magnitude) of which is groundspeed and the direction of which is known as the aircraft's track.