During an airborne VOR check, what should the omnibearing selector read when the CDI needle is centered?

When the Course Deviation Indicator (CDI) needle is centered during an airborne VOR check, the omnibearing selector, also known as the OBS (Omni Bearing Selector), should read within 6° of the selected radial. This is because VOR (VHF Omnidirectional Range) accuracy standards allow for a certain amount of deviation.

This 6° tolerance ensures that pilots can maintain situational awareness and navigate accurately while accounting for potential variations caused by equipment discrepancies, atmospheric conditions, or other factors. When the CDI needle is centered, it indicates that the aircraft is precisely following the selected radial, confirming that the VOR receiver is functioning correctly.

In contrast, the other options suggest stricter tolerances or specific situations that would not generally apply during a standard airborne VOR check, which is a straightforward procedure to verify the operational status of the VOR navigation system.