Definition
A status designation indicating that an aeronautical facility, navigation aid, runway, taxiway, lighting system, or piece of equipment is not available for operational use. The item exists but cannot be relied upon, typically due to maintenance, malfunction, or scheduled outage.
Plain English
Out of service. The equipment or facility is there, but it isn't working or isn't available to use right now.
Context Anchor
Seen in NOTAMs, airport information, equipment status reports, and pilot-controller communications when something normally available cannot be used.
Derivation
From 'serviceable,' meaning 'able to be used or put into service,' with the prefix 'un-' meaning 'not.' Literally: not in a usable state.
Why Pilots Care
Using or expecting an unserviceable item can lead to delays, diversions, or safety risks; pilots must always verify status before relying on it.
Grounding Statement
If a runway light, radio, instrument, or aid is marked unserviceable, treat it as unavailable until it is restored.
Intuition Check
Unserviceable does not just mean old, worn, or inconvenient. It means not available for safe operational use in that context.
Example Sentence 1
The NOTAM stated that runway 27 edge lights were unserviceable until 0600 local.
Example Sentence 2
Check the latest NOTAMs for any unserviceable taxiways before you taxi out.