What action is indicated by a landing gear not down alert?

The indication of a landing gear not down alert signifies that there is an issue with the landing gear system, suggesting that pilots need to take immediate corrective action to ensure safe landing. This alert prompts the crew to verify the status of the landing gear before final approach and landing, as gear not being down and locked can lead to a dangerous situation if not addressed.

Pilots are trained to perform checks and procedures in response to this alert, which may involve verifying gear indications, extending the gear manually if necessary, or following prescribed procedure to troubleshoot the situation. Taking action to ensure that the landing gear is properly deployed is critical for a safe landing. This encompasses both confirming the gear's status and preparing for any alternative procedures should the gear not be down, thus prioritizing safety without necessitating an immediate emergency landing unless further problems arise.

The other options, while they suggest urgency, do not fully encompass the proper response as indicated by the alert. Immediate landing implies a more severe scenario where landing must happen without further checks, while preparing for an emergency landing suggests that the situation has escalated beyond monitoring the gear status. Checking for cabin pressure is not directly related to the landing gear status. Hence, the correct action that encompasses the necessary steps for the situation