In what scenario is it essential for pilots to restrict aircraft movement on the ground?

Restricting aircraft movement on the ground is crucial in scenarios where the engine is running and there are no pilots onboard. In this situation, the aircraft is at risk of moving inadvertently, leading to potential collisions, accidents, or damage to the aircraft itself and surrounding objects. Maintaining strict procedures to ensure that no one is in the cockpit is essential to prevent accidental throttle inputs or system malfunctions from causing the aircraft to move unexpectedly.

Ground safety protocols mandate that if the aircraft's engines are running, there must always be a responsible person at the controls to manage the aircraft's movement. This practice ensures adherence to safety regulations and helps avoid dangerous situations that can arise from an unmonitored aircraft while it is powered.

While scenarios such as servicing the aircraft and the engine being off may also require careful management of ground movement, they do not pose the same level of immediate risk as a running engine without a pilot present. Taxiing to the runway involves controlled movement under the supervision of the pilots, who are actively managing the aircraft, making it a different context regarding safety concerns.