Definition
The published minimum altitude at which an aircraft flying a precision or vertically guided instrument approach is expected to intercept the glidepath from below. It is depicted on the approach chart at the final approach fix or precise final approach fix and ensures the aircraft meets the glidepath at a safe altitude clear of obstacles.
Plain English
The altitude shown on the approach chart where you should be level, ready to catch the descending glidepath as it comes down to meet you. You stay at this altitude until the glidepath arrives, then you start descending along it.
Context Anchor
Seen on instrument approach charts, especially where the chart shows the altitude used to join the vertical path on final approach.
Derivation
“Glidepath” combines “glide,” meaning to move smoothly downward, and “path,” meaning a route. “Intercept” comes from a Latin idea of taking or meeting something along the way. “Altitude” comes from Latin “altus,” meaning high. Together, the phrase points to the height where the airplane meets the smooth downward route to the runway.
Why Pilots Care
Reaching this altitude at the right time keeps the aircraft on a safe descent path with proper obstacle clearance.
Intuition Check
Do not read “intercept” as simply crossing the glidepath once. Here it means joining the vertical path at the proper published altitude so the descent can continue correctly. Also, “altitude” is a charted height reference, not a guess based on how high the airplane looks above the ground.
Example Sentence 1
Level at the glidepath intercept altitude of 2,000 feet, the pilot waited for the glideslope needle to center before beginning the descent.
Example Sentence 2
The pilot leveled off at the glidepath intercept altitude until the glide slope came alive.