If the position of landing gear is in doubt, how can it be verified to be down and locked?

The answer is based on the indication provided by the cockpit displays, which typically show status lights corresponding to the position of the landing gear. In aviation, a combined indication of three green lights often signifies that all three landing gears (left main, right main, and nose gear) are down and locked. This is a crucial safety measure because it provides visual confirmation to the pilots that the landing gear is in the proper position for landing.

While the gear handle position and visual checks can also provide information regarding the gear status, they may not be as definitive in confirming that all gear is both down and locked. For example, a gear handle in the DOWN position does not necessarily guarantee that the gear has successfully locked into place, and visual checks from outside might not be feasible during the flight or could be unreliable depending on the visibility conditions. Likewise, the status of landing and taxi lights being off does not directly indicate the position of the landing gear.

Thus, the combined indication of three green lights on the cockpit displays serves as the most reliable and immediate confirmation of the landing gear being down and locked, aligning with standard operating procedures in aviation safety.