Definition
An operational switch is a control that places a system, component, or facility into or out of active service. In FAA usage, OPSW typically appears in NOTAMs and facility status messages to indicate that an operational switch action has occurred or is required, such as switching a navigation aid, runway lighting system, or other equipment between operating states.
Plain English
A switch that turns a piece of equipment on or off, or changes which mode it is running in. When you see OPSW in a notice, it means something has been switched into or out of service.
Context Anchor
Seen in NOTAMs and other FAA notice text where short contractions are used to save space.
Derivation
From 'operational' (in active service or use) and 'switch' (a control that changes the state of something). Together it points to the action of changing what state a piece of equipment is operating in.
Why Pilots Care
If a NOTAM mentions an OPSW affecting a navaid, lighting system, or approach equipment you plan to use, the system's availability or mode may have changed. Catching it during preflight planning prevents surprises in flight.
Intuition Check
Do not assume switch means a cockpit toggle or electrical switch here. In this context, it means a changeover in operations.
Example Sentence 1
The NOTAM noted an OPSW on the approach lighting system, indicating it had been switched out of service for maintenance.
Example Sentence 2
During the preflight, confirm the OPSW is set to the operational position as listed in the checklist.