Definition
A defined volume of airspace centered on the runway centerline, beginning at the runway threshold and extending 200 feet beyond it, 200 feet wide (100 feet either side of centerline), and 100 feet high. It must remain clear of all obstacles, vehicles, and parked aircraft when a precision instrument approach is being conducted to that runway in weather below 250-foot ceiling or less than 3/4 statute mile (or RVR less than 4,000 feet) visibility. Only a single approved frangible visual NAVAID may be located within it.
Plain English
It's a small protected box of air just past the start of the runway. When pilots are flying a precision approach in low cloud or poor visibility, nothing — no aircraft, vehicle, or obstacle — is allowed inside that box. This gives an arriving aircraft a clean, guaranteed-clear path through the most critical part of the landing.
Context Anchor
You will see this term in airport surface operations, low-visibility procedures, runway holding instructions, and discussions of precision instrument approaches.
Derivation
‘Precision’ refers to a precision instrument approach — one that provides both vertical and horizontal guidance. ‘Obstacle Free Zone’ describes its purpose: a piece of airspace that must remain clear of obstacles. The term was introduced as airports needed tighter protection criteria for low-weather precision approaches than the standard runway safety areas provided.
Why Pilots Care
Ensures no obstacles block the initial segment of an ILS or other precision approach, directly reducing the chance of controlled flight into terrain during low-visibility landings.
Analogy
Think of the POFZ like a marked safety buffer in front of a doorway. When someone is coming through in poor visibility, that buffer must stay open so nothing is in the way.
Intuition Check
Do not read “precision” here as just “very accurate.” In this term, it points to a protected area used with precision instrument approach operations. “Obstacle free” does not mean the whole airport has no obstacles; it means this specific protected zone must be kept clear when the rule applies.
Example Sentence 1
Tower held the departing aircraft short of the runway because an arrival was inside the final approach segment and the POFZ had to remain clear.
Example Sentence 2
Any new structure near the runway threshold was reviewed to confirm it would not penetrate the POFZ.