Plain English Meaning

Things sticking up off the ground that an airplane needs to fly over or around safely — like trees at the end of a runway, a hill on the climb-out, or a radio tower near the approach path.

Full Definition

In aviation, objects on or near the ground — natural or man-made — that project high enough to interfere with the safe flight path of an aircraft, particularly during takeoff, climb, approach, and landing. Examples include trees, terrain, towers, buildings, antennas, power lines, and other aircraft.