When is it prohibited to perform a power down with passengers on board?

Performing a power down when passengers are on board is particularly prohibited during boarding or deplaning. This is primarily to ensure the safety and security of passengers as it involves potential hazards associated with abrupt power loss. If a power down were to occur during this critical phase, it could lead to confusion or a dangerous situation as passengers are moving in and out of the aircraft. Stability and functionality are essential when passengers are entering or exiting, and a sudden loss of power could compromise the operation of important systems, such as the passenger cabin lighting, entry and exit doors, or emergency systems.

The other situations, while they have their own considerations regarding safety and operational effectiveness, do not carry the same level of risk associated with passenger movement and safety as boarding or deplaning does. During turbulence, in-flight service, or taxiing, the aircraft and crew are still focused on maintaining a safe environment for passengers, but the specific risks tied to passenger movement in and out of the aircraft make boarding and deplaning a unique context for enforcing this prohibition.