What indication triggers the use of the Precautionary Emergency Landing (PEL) procedure?

The correct indication that triggers the use of the Precautionary Emergency Landing (PEL) procedure is impending engine failure. When a pilot senses or receives indications of potential engine failure, it becomes paramount to ensure the safety of the flight and its occupants. The PEL procedure is designed to allow the pilot to manage the situation proactively, giving them a structured recovery plan to safely land the aircraft in the event of an engine malfunction.

This procedure is particularly important because once engine failure occurs, options for landing become significantly limited, and swift action is needed to land as safely as possible. The PEL enables pilots to maintain control and effectively assess the situation, identify a suitable landing area, and execute a landing prior to complete power loss.

In contrast, other options, while they represent situations that may require prompt attention from a pilot, do not specifically indicate a systematic procedure like the PEL. A quick landing may be necessary in many scenarios, but it does not specifically address the severity of an impending engine failure. High altitude emergency could involve a variety of situations and is not exclusively indicative of engine issues, and low fuel warnings signal a different kind of urgency that may not necessarily correspond with an immediate need for the PEL process.