Definition
Natural or man-made objects on or near an airport that extend high enough to interfere with the safe arrival, departure, or maneuvering of aircraft. Common examples include trees, towers, antennas, power lines, buildings, terrain, and construction equipment. Obstructions affect runway usability, traffic pattern altitudes, departure climb paths, and approach minimums.
Plain English
Tall things near a runway or in the flight path that an airplane has to clear, fly around, or stay above for safety.
Context Anchor
You will see this term when learning airport traffic patterns, takeoffs, landings, runway use, and airport notes that warn about objects near the runway or flight path.
Derivation
From Latin obstruere, meaning 'to block' or 'build against.' In aviation it keeps that core sense: something standing in the way of the aircraft's path.
Why Pilots Care
Unidentified obstructions can force last-minute altitude or path changes, increasing collision risk and workload during critical phases of flight.
Intuition Check
Do not think of obstructions as only things sitting directly on the runway. In aviation, an obstruction can be beside the runway, beyond the runway, or under the flight path if it reduces the clear space an airplane needs.
Example Sentence 1
Before takeoff, the pilot reviewed the airport diagram and noted the obstructions off the departure end of Runway 27.
Example Sentence 2
Before flying the downwind leg, the student checked the sectional for obstructions that might affect the base-to-final turn.