Pushing the HDG knob will arm which lateral mode?

When the heading (HDG) knob is pushed, it arms the lateral navigation mode known as “NAV.” This action is typically associated with the autopilot system in an Airbus A320. By pushing the HDG knob, you're indicating to the autopilot system that you want to transition from the current lateral mode to navigation mode, allowing the aircraft to follow the flight management system's predefined route, which includes waypoints and airways. The NAV mode is essential for automated navigation, as it enables the aircraft to track to the next waypoint based on the flight plan entered into the Flight Management System (FMS).

Understanding how the autopilot system operates in terms of its modes is crucial for pilots as this affects how they will manage the aircraft's lateral guidance during various phases of flight. The correct identification and application of these modes can significantly influence the safety and efficiency of the flight.