What does the EXT PWR AVAIL light indicate?

The EXT PWR AVAIL light serves as an important indicator of the aircraft's external power source status. When this light is illuminated, it specifically means that the external power is plugged in and that the electrical parameters being supplied—such as voltage and frequency—are within acceptable and normal limits. This confirmation is vital for the ground crew and flight crew, as it assures that the aircraft can rely on external power for systems operation, thus allowing the aircraft's internal batteries to remain charged and conserving their use for when the aircraft is not connected to an external power source.

This light does not simply indicate that external power is connected; it also provides essential confirmation that the power meets the necessary parameters to safely power the aircraft's systems. Understanding this indication is crucial for ground operations, ensuring the aircraft's readiness and safety before taxiing or prior to flight.