What is advised when encountering flashing beacons on aircraft?

When encountering flashing beacons on aircraft, the advised action is to watch for the engine starting. This is crucial for safety reasons, as flashing beacons typically indicate that the aircraft is preparing for engine start-up or is already in the process of doing so. During this time, the aircraft's engines may be about to start and could generate significant thrust that can cause movement or create a dangerous situation for personnel or vehicles nearby.

Being vigilant and monitoring the aircraft for signs of engine activity, such as the initiation of engine starts or any movement, helps ensure that you can react appropriately, maintain a safe distance, and avoid any potential hazards associated with aircraft operation.

The other options, such as approaching quickly, ignoring the beacons, or driving as close as possible to the aircraft, do not prioritize safety and could lead to accidents or injuries, as they either encourage unnecessary haste or mitigate the awareness necessary to protect oneself and others when an aircraft is active.