Definition
The difference between the bearing indicated by a navigation receiver (such as a VOR) and the actual, known correct bearing. When testing a VOR using a VOT, the bearing error is the deviation between the displayed radial and the expected reference radial, and must fall within published tolerances for the equipment to be considered legal for IFR use.
Plain English
How far off the navigation instrument's reading is from the true, correct value. A small error is normal; too much error means the equipment cannot be trusted for instrument flying.
Context Anchor
Seen when checking a VOR receiver with a VOT before using it for instrument navigation.
Derivation
Bearing comes from an older use of bear meaning to point, carry, or hold a direction. Error comes from a Latin word meaning to wander. Together, bearing error means the direction indication has wandered away from where it should be.
Why Pilots Care
Reveals whether the VOR system meets the accuracy required for safe instrument navigation.
Intuition Check
Bearing error does not mean the airplane is flying the wrong heading. It means the navigation receiver’s direction indication is off by a certain number of degrees.
Example Sentence 1
After tuning the VOT frequency, the pilot centered the needle and noted a bearing error of two degrees, well within the allowable tolerance.
Example Sentence 2
A bearing error exceeding four degrees means the VOR receiver must be serviced before IFR use.