Final answer:
The Arming VNAV System is armed by programming the desired flight profile into the Flight Management System and selecting the VNAV mode on the Flight Control Unit in fly-by-wire aircraft. This pre-flight action prepares the aircraft for efficient vertical navigation during flight.
Step-by-step explanation:
The VNAV (Vertical Navigation) system is armed through the Flight Control Unit (FCU) by inputting the desired flight profile into the flight management system (FMS). This is typically done by the pilot before takeoff or during the pre-flight planning stage.
In modern fly-by-wire aircraft, the VNAV function can manage the aircraft's altitude, airspeed, and vertical speed based on the programmed flight plan.
To arm the VNAV system, the pilot will program the route, altitude constraints, and performance data into the FMS. Once this information is confirmed and the VNAV mode is selected on the FCU, the system is armed and ready to be engaged.
When active, VNAV will control the aircraft's vertical path to follow the pre-determined flight profile, adjusting for the most efficient climb, cruise, and descent profiles.