VOR Test Signal

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.

Definition

A dedicated ground-based radio signal used to verify the accuracy of an aircraft's VOR (VHF Omnidirectional Range) navigation receiver. The signal is transmitted on a specific frequency from a VOR Test Facility (VOT) and produces a known, fixed reference bearing on the aircraft's VOR indicator, allowing the pilot to confirm the receiver's accuracy is within tolerance before flight.

Plain English

A test signal sent from the ground that lets a pilot check whether their VOR navigation equipment is reading correctly. When tuned in, it should show a known, predictable result on the cockpit display. If it does, the equipment is good to use.

Context Anchor

You will encounter this during a VOR equipment accuracy check, often before using VOR navigation on an instrument flight.

Derivation

VOR comes from VHF Omnidirectional Range — a navigation system using Very High Frequency radio signals that broadcast in all directions (omni = all, directional = direction). The 'test signal' part is exactly what it sounds like: a signal designed to test the equipment, not to navigate by.

Why Pilots Care