How does an ILS approach get captured and flown with the A321?

• A. In APP mode, the aircraft follows the localizer and glideslope; autopilot/flight director maintains the approach path until landing or handoff to pilot.
• B. The crew manually tracks the localizer; autopilot disconnects.
• C. It uses GPS guidance only.
• D. It follows the runway centerline by visual cues.

Answer: (A)

The main idea is that an ILS approach on the A321 is captured and flown by the automatic flight control system in approach mode. The localizer gives lateral guidance and the glideslope provides vertical guidance. When you select approach mode and tune the ILS, the system automatically captures the localizer and then the glideslope, and the autopilot (with the flight director) flies the aircraft on that path. It keeps you centered on the runway centerline and on the proper descent path until you land or until you hand the controls back to the crew. In CAT II/III operations, the system can even perform the landing automatically, but for normal operations the autopilot remains engaged until touchdown or until the crew disconnects.

This is distinct from manually tracking the localizer with the autopilot off, using GPS guidance only, or following the runway visually. Those scenarios either don’t rely on the ILS signals or rely on visual cues rather than the instrument guidance used for an ILS approach.