Definition
The number of degrees by which the bearing to or from a navigation station shifts over a given period of time as the aircraft moves through the air. In the time and distance check using a Radio Magnetic Indicator (RMI), the rate of bearing change is used together with elapsed time and groundspeed to calculate time and distance to the station.
Plain English
How much the needle pointing at the station has swung around the compass card during a set period of flying. A bigger swing in less time means you are closer to the station; a smaller swing means you are farther away.
Context Anchor
Used during a time-and-distance check from a radio navigation station, such as when watching the pointer on a radio magnetic indicator.
Derivation
Bearing comes from an older use of “bear” meaning to point, move, or lie in a direction. In navigation, a bearing is the direction from one place to another, so a bearing change is the amount that direction has shifted.
Why Pilots Care
It lets a pilot calculate distance from the station without DME by timing a known bearing shift.
Analogy
As you pass a landmark in a car, its direction out the window changes slowly when it is far away and quickly when you are close. Bearing change works the same way: the rate of change helps show how close you are to the station.
Intuition Check
Bearing change does not mean the aircraft changed heading. It means the measured direction to the station changed.
Example Sentence 1
Flying a steady heading perpendicular to the bearing, the pilot timed a 10-degree bearing change and used it to estimate the distance to the VOR.
Example Sentence 2
Faster bearing change means the aircraft is getting closer to the station.