Definition 1 of 2
Definition
A specially radiated signal, called a VOT, transmitted at certain airports for the sole purpose of allowing pilots to check the accuracy of their VOR navigation receivers. When tuned to the published VOT frequency, a correctly functioning VOR receiver will indicate 0 degrees TO or 180 degrees FROM, regardless of the aircraft's position on the airport. FAA tolerance is plus or minus 4 degrees.
Plain English
A test radio signal at some airports that lets you check whether your VOR navigation equipment is reading correctly before you fly. If the equipment is healthy, the needle and indicator will read a known, expected value.
Context Anchor
Encountered during a preflight VOR accuracy check, especially before instrument flight from an airport that provides a VOR test facility.
Derivation
VOR comes from “VHF omnidirectional range.” “VHF” means very high frequency, the radio band used, and “omnidirectional” means the signal works in all directions around the station. “Test signal” tells you this broadcast is meant to check the receiver, not guide the airplane along a route.
Why Pilots Care
Confirms the VOR receiver is accurate before relying on it for navigation.
Intuition Check
Do not treat a VOR test signal as a navigation signal to fly toward or away from. It is a known reference used to check whether the airplane’s VOR receiver is indicating correctly.
Example Sentence 1
Before the IFR cross-country, the pilot tuned the VOT frequency on the ramp and confirmed the VOR was reading within tolerance.
Example Sentence 2
Maintenance used the Vor Test Signal to confirm the receiver was within tolerance after installing a new navigation unit.