Definition
Obstacles whose location, height, and presence are documented on aeronautical charts, in instrument procedure designs, or in official obstruction databases, and which are accounted for in published minimum altitudes and obstacle clearance criteria.
Plain English
Things sticking up from the ground — like towers, mountains, or buildings — that the FAA already knows about and has drawn on charts, so published altitudes are designed to keep aircraft safely above them.
Context Anchor
Seen in instrument procedure, departure, approach, missed approach, and obstacle clearance discussions.
Why Pilots Care
Instrument minimum altitudes are calculated to provide safe clearance over all known obstacles; missing one can result in controlled flight into terrain.
Intuition Check
“Known” does not mean personally known by the pilot or visible from the cockpit. Here it means identified in the information used to design or evaluate the flight path.
Example Sentence 1
Flying at the published MEA keeps the aircraft clear of all known obstacles along that route segment.
Example Sentence 2
Pilots review the sectional chart to locate known obstacles before departing into mountainous terrain.