Definition
The Obstacle Free Zone (OFZ) is a defined volume of airspace centered above the runway and its approach and departure surfaces, kept clear of all fixed objects except frangible visual navigation aids needed for air navigation. It protects aircraft from the final approach through the start of the takeoff climb, and includes the runway OFZ, the inner-approach OFZ, and the inner-transitional OFZ.
Plain English
It is a protected pocket of air above and around the runway that must stay clear of obstructions, so aircraft landing or taking off have a guaranteed clean path.
Context Anchor
You may see this term in airport design information, runway safety discussions, instrument approach planning, and air traffic control procedures for keeping runways clear.
Derivation
Obstacle means something that blocks or gets in the way. Free means clear of that thing. Zone means a defined area. Together, the words point to a specific protected area that is kept clear of obstacles for aircraft movement near a runway.
Why Pilots Care
Maintains a guaranteed clear path during the most critical moments of takeoff and landing, especially in low visibility, reducing the risk of collision with objects near the runway.
Grounding Statement
Picture the runway with an invisible protected box of air around it that must stay clear while aircraft are operating near the ground.
Intuition Check
Obstacle Free Zone does not mean the whole airport has no obstacles. It means a specifically defined protected space around a runway must be kept clear except for limited, controlled exceptions.
Example Sentence 1
The tower held the departing aircraft because a maintenance truck was still inside the Obstacle Free Zone.
Example Sentence 2
Airport maintenance delayed placing a new sign because it would have penetrated the Obstacle Free Zone.