Mission System Operator (MSO) Standardization Practice Test

The Inmarsat terminal is powered by the aircraft’s avionics power system, so it comes online when avionics power is up. This integration ensures the satellite communication equipment initializes with the rest of the onboard avionics, using the same power bus and control signals for proper startup and operation. It isn’t activated just after engine start, nor solely when the APU is running, and it isn’t limited to external power only. External power can supply the aircraft, but the activation condition for the Inmarsat terminal remains the availability of the avionics power.