How should an operator respond if an excavator begins rolling downhill?

When an excavator begins rolling downhill, the proper response is to engage the controls to stabilize the machine and avoid any sudden movements. This response is crucial because the operator can use the controls to maintain control over the excavator, potentially preventing it from rolling further or tipping over. Engaging the controls helps to ensure that the bucket or arm can be used to dig into the ground, creating resistance to stabilize the machine and reduce the risk of an accident.

Jumping off the machine immediately would be dangerous, as the operator could be injured by falling or by the equipment rolling over. Turning off the engine may not provide immediate assistance in controlling the situation and could even increase the risk of losing control if the machine continues to move. Calling for help before acting would delay necessary interventions, which can be critical in a situation where immediate action may be required to prevent injury or damage. Therefore, engaging the controls is the most logical and effective reaction to regain control of the excavator in an emergency situation.