What action should be taken if the landing gear fails to indicate down?

When the landing gear fails to indicate that it is down, executing the gear emergency extension procedure is the appropriate action to take. This procedure is specifically designed to address situations where the landing gear position is uncertain and ensures that the gear can be safely deployed for landing. The emergency extension mechanism allows pilots to lower the landing gear manually, thus providing a high level of confidence that the aircraft will be in a safe condition for landing.

Increasing altitude may delay the situation but does not resolve the problem of the landing gear indicator. Continuing flight and reporting to ATC can be dangerous, as it does not address the immediate need for ensuring the landing gear is down before landing. Landing immediately without confirming the gear status could result in a gear-up landing, leading to significant damage to the aircraft and potential danger to those onboard. Therefore, executing the gear emergency extension procedure is the proper and safest course of action in this scenario.