In what scenario would the generator be selected offline?

The selection of the generator to be offline when the ENG FIRE switch is pressed is based on safety protocols and procedures in aviation. When an engine fire is detected, the ENG FIRE switch is designed to manage the situation by shutting down the engine and simultaneously taking measures to mitigate the risk of fire. This may involve shutting down the generator associated with that engine to prevent further electrical supply that could exacerbate safety issues.

Choosing to take the generator offline in this scenario helps to ensure that systems powered by that generator are also secured, reducing the risk of electrical faults and allowing the flight crew to focus on emergency procedures without the complications of a potentially dangerous electrical system. This action can help optimize the safety of the aircraft and its occupants in a critical situation, providing a clear and decisive response to a fire emergency.

In the other scenarios presented, such as standard operations, low fuel levels, or during landing, the generator would typically remain online to power essential systems needed for flight and safety. Hence, the action to take the generator offline is specifically warranted during an emergency situation like an engine fire, emphasizing the priority of safety and control in managing aircraft systems.