What is captured during an ILS approach and what mode controls it?

• A. The localizer and glideslope are captured; APP mode with autopilot/flight director maintains the approach path.
• B. The localizer only is captured; heading reference mode controls it.
• C. The glideslope is ignored; manual flight is required.
• D. GPS guidance captures the approach; LNAV mode controls it.

Answer: (D)

An ILS approach uses two signals to guide the aircraft: the localizer for horizontal alignment with the runway centerline and the glideslope for vertical descent along the proper path. When you fly the approach with automation, you typically use the approach mode (APP) on the autopilot/flight director, which couples to the ILS signals. Locally, you might see the autopilot first track the localizer (LOC) for lateral guidance, and once established, it can capture the glideslope (GS) to follow the vertical path. This combination keeps the aircraft on the ILS path down to the runway. GPS-based LNAV guidance does not control the ILS signals; LNAV is for RNAV/GPS lateral navigation, not for capturing the ILS localizer and glideslope.