What control system does the PMU use to switch between flight and ground modes?

• A. Weight-on-wheels switches
• B. Throttle control
• C. Altitude sensors
• D. Fuel pressure sensors

Answer: (A)

The PMU, or Power Management Unit, utilizes weight-on-wheels switches to determine whether the aircraft is on the ground or in flight. This is crucial because the flight control systems need to adjust their operational modes based on the aircraft's state. When the aircraft is on the ground, specific systems may need to be disabled to prevent accidental activation of flight maneuvers or to ensure safety checks are fulfilled before takeoff. Conversely, when the aircraft is airborne, the PMU activates the necessary flight parameters to ensure optimal performance. This transition mechanism ensures that the flight control systems are appropriately configured and responsive to the aircraft's operation environment, enhancing both safety and efficiency.

Other systems like throttle control, altitude sensors, and fuel pressure sensors may play roles in overall aircraft performance and safety but are not specifically responsible for switching between ground and flight modes. Their functions are related to operational parameters during flight rather than the initial determination of the aircraft's state based on weight and ground contact.