Pushing the MAN ON switch extends the RAT under what condition?

The correct answer is that the RAT (Ram Air Turbine) can be extended anytime since it is always powered when the MAN ON switch is activated. This means that regardless of the airplane's situation, whether it’s on the ground or in the air, as long as the MAN ON switch is pushed, the RAT will deploy.

The RAT serves as an emergency power source, providing hydraulic and electrical power in case of total power loss from the aircraft's usual sources. The RAT is designed to be operational under conditions that necessitate its use, which is why it does not require specific flight conditions like being airborne or having the engines running.

In contrast, the other options imply restrictions that are not consistent with how the RAT functions. For instance, suggesting that it can only be deployed on the ground with engines running limits its utility in emergency scenarios and overlooks its design for emergency operation regardless of engine status or flight conditions. Therefore, understanding that the RAT can be activated under any circumstances reinforces the critical nature of this safety feature in maintaining aircraft operability during emergencies.