Which condition is most likely to activate the landing gear warning signal?

The condition that activates the landing gear warning signal is closely associated with the configuration of the aircraft during the approach for landing. When the power levers are retarded to idle, the flaps are up, and the landing gear lever is locked in the up position, this creates a significant risk. The system is designed to alert the flight crew that the aircraft may be approaching landing with the landing gear not deployed, which is a critical safety concern.

In this scenario, the combination of retarding the power levers to idle and having the flaps up indicates that the aircraft is in a landing configuration but the landing gear is not extended. This prompts the warning signal to activate, alerting the crew to the oversight. The warning system is intentionally designed to trigger under such circumstances to prevent the aircraft from landing without the gear being down and locked, thereby averting a potentially catastrophic situation.

The other circumstances involve either having the landing gear properly extended and locked or being in configurations where the landing gear is not a concern, which would not prompt a warning. Understanding the specific parameters under which the warning signal activates assists pilots and flight engineers in maintaining awareness of critical flight safety protocols.