Definition
An indication on the landing gear position indicator system showing that the landing gear is not confirmed down and locked in the position required for landing. It is typically signaled by a red warning light and means at least one gear leg has not reached the fully extended and locked state.
Plain English
A warning that the wheels are not confirmed all the way down and locked, so the airplane should not be landed yet.
Context Anchor
Seen on or near landing gear controls and position indicators in airplanes with retractable landing gear.
Why Pilots Care
If the gear is not down and locked, touchdown can collapse the landing gear. The red 'unsafe' indication is a direct cue to stop, troubleshoot, run the gear malfunction checklist, and not continue the approach to landing until the gear is confirmed safe.
Intuition Check
Do not read unsafe for landing as a general opinion about the weather, runway, or pilot skill. In this context, it means the airplane itself is not indicating a safe landing configuration, especially the landing gear position.
Example Sentence 1
On final approach, the pilot saw the red 'unsafe for landing' light, executed a go-around, and ran the landing gear malfunction checklist.
Example Sentence 2
During the pre-landing check, confirm there are no unsafe for landing lights or flags before continuing the approach.