In LNAV routing within Australia, the track between two waypoints is based on which geometry?

• A. Great circle
• B. Rhumb line
• C. Direct bearing
• D. Constant heading

Answer: (A)

Great-circle geometry is used for LNAV routing between waypoints. On a spherical Earth, the shortest path connecting two points is a great-circle arc, and aviation systems use that geometry to define each leg from one waypoint to the next. This minimizes distance and fuel burn, especially over longer legs. On flat-map charts the path often looks curved because it’s the projection of a globe’s great-circle route, even though the aircraft’s navigation system computes and follows that arc.

A rhumb line, by contrast, would keep a constant bearing relative to north and would not represent the shortest path between the points, leading to longer distances. A direct bearing or a constant heading describes different notions of direction or motion that don’t define the actual curved path used between waypoints. Hence, the appropriate geometry for LNAV legs is the great circle.