For an RNAV approach, arming Approach Mode requires which conditions to be met?

• A. FMS is selected, RNAV procedure is loaded, flight plan is not modified, and distance to the airport is less than 30 miles
• B. FMS is not selected, RNAV loaded
• C. RNAV loaded but distance greater than 30 miles
• D. Flight plan modified

Answer: (A)

The main idea is that RNAV Approach Mode is a controlled readiness to fly the published RNAV approach, and it will only arm when the system can reliably follow the procedure. To arm it, the FMS must be the active nav source and the RNAV procedure must be loaded so the cockpit knows which final path to follow. The flight plan should remain unchanged so the system recognizes the active approach leg and doesn’t reset or cancel the arm sequence. Being within a specific distance from the airport ensures you’re in the appropriate terminal region and the GPS-guided path can be captured smoothly; this distance threshold prevents arming too early while you’re still in en-route or in transition.

If the FMS isn’t selected or the RNAV procedure isn’t loaded, there’s no valid RNAV approach path for the system to follow, so arming isn’t appropriate. If you modify the flight plan, the system may no longer have a stable, recognized approach in progress, which can prevent arming. If you’re farther than about 30 miles from the airport, you’re outside the capture region for the approach path, and arming would be premature or unreliable.

So the best condition combination is having the FMS active, the RNAV procedure loaded, the flight plan unchanged, and being within 30 miles of the airport.