Definition
A ground-based radio facility that transmits a specific test signal allowing pilots to check the accuracy of their aircraft's VOR receiver. When tuned to the published VOT frequency, the receiver should indicate the 360° radial with a FROM indication, or the 180° radial with a TO indication, regardless of the aircraft's position on the airport. Permitted error is plus or minus 4°.
Plain English
A small radio transmitter on the ground at certain airports that lets a pilot confirm their VOR navigation receiver is reading correctly before flight. The needle should center on a known reading; if it doesn't, the receiver is off and may not be legal for instrument flight.
Context Anchor
You encounter VOTs when performing a VOR receiver check before using VOR navigation, especially for instrument flying.
Derivation
VOR stands for Very High Frequency Omnidirectional Range. The 'T' in VOT simply marks it as a Test version of that signal. Knowing this helps the pilot remember it is a calibration tool, not a navigation aid.
Why Pilots Care
Confirms VOR receiver accuracy within required tolerances, directly supporting safe navigation and regulatory compliance.
Intuition Check
A VOT is not a normal navigation station to fly toward or away from. It is a known test signal used to see whether the airplane’s VOR receiver is reading correctly.
Example Sentence 1
Before the IFR cross-country, the pilot tuned the VOT frequency listed in the Chart Supplement and confirmed the CDI centered with a FROM indication on the 360° radial.
Example Sentence 2
After maintenance on the avionics, the mechanic used the VOT signal to confirm the VOR receiver met tolerance limits.