When will the "landing gear unsafe" light illuminate?

The "landing gear unsafe" light illuminates when sensors detect low hydraulic pressure. This situation indicates that the landing gear may not be fully deployed or locked into position properly because sufficient hydraulic pressure is essential for the mechanism that extends and locks the landing gear in place. If low pressure is detected, it suggests that the gear might not be in a safe condition, prompting the warning light to alert the pilot.

In contrast, the other scenarios involve conditions where the landing gear should function properly. When the landing gear is fully deployed, the light should not illuminate, reflecting that the gear is in a safe, fully extended position. Activating the hydraulic pump may not specifically trigger the warning light, as this action is a normal part of maintaining hydraulic pressure rather than an indicator of a problem. Additionally, when the gear is retracted, the light typically remains off unless there is a specific issue, as the system does not indicate an unsafe condition in that state unless there is a failure detected.