Definition
A large-scale chart published by the National Geodetic Survey (formerly the National Ocean Service) that depicts an airport's runways, taxiways, and the location, height, and type of every significant obstruction within the airport's defined approach and departure surfaces. The chart is used by airport planners, designers, and aeronautical authorities to assess obstacle clearance and to support the design of instrument procedures.
Plain English
A detailed map of an airport that shows exactly where tall objects -- buildings, towers, trees, terrain -- are located near the runways, along with how high they are. It is used to make sure aircraft have safe clearance when taking off and landing.
Context Anchor
Seen in airport planning, obstacle review, and discussions about safe approach and departure paths.
Derivation
The word obstruction comes from the Latin obstructio, meaning 'a blocking up' or 'something that stands in the way.' On this chart, an obstruction is anything tall enough to potentially interfere with aircraft on or near the airport.
Why Pilots Care
Knowing obstacle locations and heights lets pilots calculate required climb gradients and choose safe departure or arrival routes.
Grounding Statement
Picture looking down at an airport map and seeing the runways along with nearby towers, hills, buildings, or other objects that could matter to an aircraft close to the ground.
Intuition Check
An obstruction is not just any object near an airport. On this chart, it means an object or terrain feature that may matter because of its height, location, and effect on protected flight paths.
Example Sentence 1
The procedure designers consulted the Airport Obstruction Chart to confirm that the new departure path provided adequate clearance over the surrounding terrain.
Example Sentence 2
The Airport Obstruction Chart helped the crew plan a non-standard departure that avoided the construction cranes near the airport boundary.