Definition
A built-in self-check function on certain cockpit indicator and warning lights, activated by pressing the lens or button of the light to verify that the bulb and circuit are working. When pressed, a functioning light illuminates; if it does not illuminate, the bulb is burned out or the circuit has failed.
Plain English
Push the warning light to make sure it still works. If it lights up, the bulb is good. If it stays dark, the bulb is broken.
Context Anchor
Seen on cockpit warning and position lights, including landing gear position lights and other panel indicators checked before or during flight.
Why Pilots Care
Confirms that critical warning lights will activate if a real problem occurs, avoiding undetected failures.
Intuition Check
Do not assume “press to test” tests the whole airplane system. It usually tests whether the light or display can turn on.
Example Sentence 1
During the before-takeoff check, the pilot used press to test on each gear position light to confirm all three bulbs were good.
Example Sentence 2
When one light stayed dark during press to test, the pilot replaced the bulb before starting the engine.