Definition
The vertical guidance component of an Instrument Landing System (ILS) or similar precision approach. It transmits a narrow radio beam angled upward from a point near the runway touchdown zone, providing the pilot with a precise descent path to the runway.
Plain English
An invisible sloping radio beam that tells the pilot whether they are too high, too low, or right on the proper descent angle to the runway.
Context Anchor
Seen in helicopter instrument procedure notes, operations specifications, and speed limits that are based on how fast the helicopter moves over the ground.
Derivation
From 'glide' (a controlled descent without power increase) and 'slope' (an inclined line). Together they describe the angled descent path the aircraft follows down to the runway.
Why Pilots Care
A correctly functioning GS allows a stabilized descent that meets obstacle clearance and runway alignment requirements; loss of the signal forces a missed approach or transition to a non-precision procedure.
Grounding Statement
With a tailwind, a helicopter can cover the ground faster even though it is being flown at the same speed through the air.
Intuition Check
Do not assume GS always means glide slope. In this helicopter operations-specification context, GS means ground speed.
Example Sentence 1
Once established on the localizer, the pilot intercepted the GS and began the descent to the runway.
Example Sentence 2
When the GS flag appeared on the instrument, the pilot immediately initiated the missed approach procedure.