Definition
A radio navigation signal that provides vertical guidance to an aircraft on final approach to a runway, defining the correct descent angle (typically 3 degrees) from the final approach fix down to the runway touchdown zone. It is the vertical component of an Instrument Landing System (ILS), paired with the localizer which provides lateral guidance.
Plain English
An invisible sloping radio beam projected from near the runway that tells the pilot whether they are descending at the right angle as they come in to land. If the aircraft drifts above or below this beam, a cockpit indicator shows which way to correct.
Context Anchor
You will see this term during instrument approach training, on approach briefings, and when checking whether the aircraft is too high or too low on final approach.
Derivation
Glide refers to a controlled descent without added power; slope refers to an inclined line. Together: the inclined path the aircraft follows as it descends toward the runway.
Why Pilots Care
Allows safe, precise landings in low visibility by maintaining the correct descent angle to the runway threshold.
Grounding Statement
Picture a shallow, invisible ramp leading down through the air to the runway touchdown area.
Intuition Check
Glide slope does not mean the slope of the runway or the ground. It means the aircraft’s intended downward path through the air toward landing.
Example Sentence 1
The pilot intercepted the glide slope and began a steady descent toward the runway.
Example Sentence 2
When the glide slope indicator showed a fly-up command, the aircraft was below the proper path.