Definition
The Inner-Approach OFZ is a defined volume of airspace centered on the approach area of a runway with an approved instrument approach. It begins 200 feet beyond the runway threshold, extends 200 feet outward from the runway centerline on each side, and stretches 900 feet along the extended runway centerline. Within this volume, no fixed object (other than frangible visual navigation aids that must be there) is permitted to penetrate. It applies only to runways served by an approved instrument approach with vertical guidance.
Plain English
It is a protected block of air just past the threshold of certain runways. Nothing solid is allowed to stick up into it, so an aircraft on final approach has guaranteed clearance from obstacles in that critical zone.
Context Anchor
Seen in airport design, runway protection, and approach-lighting discussions, especially for runways served by approach lights.
Derivation
"Inner" means closer in toward the runway. "Approach" refers to the path an aircraft flies as it descends to land. "OFZ" stands for Obstacle Free Zone — literally, a zone kept free of obstacles. Together, the name describes the inner portion of the approach path that must remain clear of any solid object.
Why Pilots Care
Maintaining this zone free of obstacles ensures the required clearance margins during low-visibility or instrument approaches, directly affecting landing safety and go-around decisions.
Analogy
Think of it as a clear tunnel leading toward the runway. The tunnel starts low near the threshold and slopes upward along the approach lights.
Intuition Check
“Inner-approach” does not mean the final part of an instrument approach procedure. Here it means a specific protected area near the runway threshold and approach lights.
Example Sentence 1
The new taxiway sign was designed to be frangible so it would not violate the Inner-Approach OFZ.
Example Sentence 2
Airport operations verified that temporary equipment had been removed from the Inner-Approach OFZ prior to resuming night landings.