ATPL Canadian Meteorology, Radio Aids to Navigation, and Flight Planning (SAMRA) Practice Test 2025 - Free ATPL Practice Questions and Study Guide

In a VOR (VHF Omnidirectional Range) navigation system, the indication of how far off course an aircraft is can be deduced from the movement of the course deviation indicator, or CDI. When the aircraft is flying on a set course to or from a VOR station, the CDI will display the position of the aircraft relative to that course.

When you are 10 nautical miles away from a waypoint, each dot on the CDI typically represents a specific distance off course, which is fundamentally linked to the distance from the VOR station. The standard convention for VOR indicators is that each dot on the CDI equates to a specific distance off course. At a range of 10 nautical miles, a single dot generally signifies a deviation of approximately 1 nautical mile from the desired course. Therefore, if the aircraft moves one dot away from the center of the CDI, it indicates that the aircraft is 1 nautical mile off course from the route being followed.

This understanding is crucial for pilots in maintaining their intended flight path and for determining necessary corrections to stay on track. Each degree of deviation also influences the pilot's navigation decisions, highlighting the importance of accurately interpreting the VOR signals and indications.