Definition
A NOTAM contraction indicating that an object, obstruction, hazard, or area lacks the visual markings (paint, flags, or similar daytime identifiers) normally expected to make it conspicuous to pilots.
Plain English
It means something out there does not have the usual paint, flags, or other visible markings that would normally make it easy to see.
Context Anchor
Seen in NOTAMs and airport condition information, especially when describing construction areas, obstacles, closed surfaces, or hazards.
Derivation
Unmarked comes from un-, meaning “not,” plus marked, meaning “shown or identified with a visible sign or symbol.” In aviation, that points to something that may be present but not easy to identify by normal visual markings.
Why Pilots Care
Pilots must know when markings are absent because it reduces visual guidance for landing, taxiing, and avoiding hazards.
Intuition Check
UNMKD does not mean the item is unknown or missing from all records. It means the item is not visually marked where a pilot or vehicle operator would expect to see markings.
Example Sentence 1
The NOTAM reported a 250-foot crane UNMKD near the approach end of the runway, so we planned a wider downwind to stay clear.
Example Sentence 2
After landing on the UNMKD taxiway, the crew followed the controller’s directions closely to stay on the correct path.