Definition
A small mechanical or electrical flag inside a navigation instrument that appears in view to warn the pilot that the displayed information is unreliable or that the signal being received is too weak to use. When the blinker is showing, the indication on that instrument should not be trusted for navigation.
Plain English
A warning flag that pops into view on a navigation gauge to tell you the instrument isn't getting a usable signal, so don't rely on what it's showing.
Context Anchor
Seen in aircraft lighting, warning indications, and older aviation descriptions of flashing signal lights.
Derivation
From the verb 'blink,' meaning to appear and disappear suddenly. The flag 'blinks' into view when the signal fails and disappears when reception is restored, which is where the name comes from.
Why Pilots Care
Increases the chance that other traffic will spot the aircraft, reducing collision risk during night or low-visibility operations.
Intuition Check
Do not assume “blinker” means an automobile turn signal. In aviation, it can refer more generally to any light or light-control device that flashes to signal something.
Example Sentence 1
When the VOR blinker came into view, the pilot stopped using that station for navigation and switched to the second receiver.
Example Sentence 2
During the preflight the instructor verified that the blinker flashed at the correct rate.