When using Nav Preview to aid final approach course switching, which mode must be armed?

• A. APR mode.
• B. NAV mode.
• C. FMS mode.
• D. VOR mode.

Answer: (A)

Nav Preview is all about setting up and previewing the final approach course so you can switch to it cleanly. To actually fly that final approach path once you switch, the autopilot needs to be in Approach mode. Arm-ing APR tells the autopilot to capture and follow the published approach course as the active path, rather than continuing to track the current navigation source or a different leg. That’s why APR is the mode you must arm when using Nav Preview to aid final approach course switching. NAV mode would just follow the current nav source, VOR mode would lock to a VOR signal, and FMS mode would follow the flight plan, not the fresh approach course you’re previewing.