What is the acceptable error during a VOT check in degrees?

During a VOT (VOR Test Facility) check, the acceptable error is established to ensure that the navigation system is functioning correctly and providing accurate guidance. The limit set for deviation from the published VOT frequency signal in such a check is ±4 degrees. This means that if you are using a VOR receiver to check against the VOT signal, your reading should not differ more than 4 degrees from the expected value in order to be considered within acceptable tolerances.

This standard is important for maintaining safety and reliability in navigation, especially during instrument flight when precise navigation is critical. A deviation beyond this limit could indicate a malfunction in the VOR equipment or in the pilot's navigation procedures, potentially leading to a hazardous flying environment.