Definition
The vertical height, in feet, that an aircraft must clear above the runway surface to safely pass over an obstruction at the end of the takeoff path. On takeoff performance charts, this is typically given as 50 feet, representing the standard obstacle the aircraft must clear during a takeoff distance calculation.
Plain English
The height of an imaginary or real object at the end of the runway that the airplane has to fly over after lifting off. Charts usually use 50 feet as the standard height to plan for.
Context Anchor
Seen when using takeoff charts to calculate whether the airplane can safely clear trees, wires, terrain, or a standard chart obstacle after takeoff.
Derivation
Obstacle comes from Latin words meaning something that stands in the way. Height simply means vertical distance. Together, obstacle height points to the vertical size of what the airplane must get over.
Why Pilots Care
Directly determines whether the aircraft meets the climb performance needed to depart safely without striking objects near the runway.
Intuition Check
Obstacle height is not the airplane’s height during the takeoff roll. It is the height of the object or clearance point the airplane must climb above after liftoff.
Example Sentence 1
The chart showed a takeoff distance of 1,500 feet over the 50-foot obstacle height, so the pilot confirmed the runway and clear area were long enough.
Example Sentence 2
With a 35-foot obstacle height shown beyond the runway end, the chart indicated a higher climb rate was needed before turning.