Definition
A NOTAM contraction indicating that a runway, taxiway, navigation aid, lighting system, instrument approach procedure, or other airport facility or service is not available for use, either temporarily or until further notice.
Plain English
A short way of saying something at the airport — like a runway, taxiway, light, or navigation aid — cannot be used right now.
Context Anchor
Seen in NOTAMs and airport information when a specific airport item or service cannot be used.
Derivation
Unusable comes from un-, meaning “not,” plus usable, meaning “able to be used.” The NOTAM contraction UNUSBL shortens the word so it can be shown quickly in aviation notices.
Why Pilots Care
A pilot who misses an UNUSBL notice may attempt to use equipment that is unsafe or inoperative.
Intuition Check
Do not read UNUSBL as “not ideal” or “use with caution.” In this context, it means the item should not be used for the operation being described.
Example Sentence 1
The NOTAM stated RWY 14/32 UNUSBL due to construction, so the pilot planned to use the crosswind runway instead.
Example Sentence 2
Runway 09 was listed as UNUSBL because of snow removal in progress.