What type of guidance does the glide slope provide in an ILS approach?

The glide slope provides vertical guidance in an Instrument Landing System (ILS) approach by defining the correct descent angle for an aircraft to follow as it approaches the runway. It is designed to ensure that the aircraft descends at an appropriate rate to reach the runway threshold safely while maintaining a safe distance from the ground during the approach. This vertical guidance is typically depicted as a beam that the aircraft follows, providing precise instructions on how to adjust their altitude during the descent.

While lateral guidance is provided by the localizer component of the ILS, which directs the aircraft left or right to align with the runway centerline, the glide slope specifically deals with ensuring that the aircraft is at the correct height at various points during the approach. Speed guidance and altitude guidance are not functions of the glide slope; instead, speed is managed by the pilot and air traffic control, and altitude in terms of maintaining level flight may be indicated by other means but does not directly involve the glide slope's function in an ILS approach.