Final answer:
The maximum allowed variation between two indicated bearings when checking a VOR system against each other while airborne is 4 degrees, which is critical for maintaining accurate air navigation.
Step-by-step explanation:
When checking a VOR system against another, the maximum variation between two indicated bearings while airborne should not exceed 4 degrees. The accuracy of the VOR system is critical for air navigation, and periodic checks against known ground references or other airborne methods are conducted to ensure the VOR is providing accurate bearings for aircraft navigation.
When checking a VOR system against each other in an airborne state, the maximum variation between two indicated bearings is 4°. This means that the bearings can differ by up to 4° from each other.
For example, if one VOR system indicates a bearing of 100°, the other VOR system can indicate a bearing between 96° and 104°.
This variation is caused by factors such as the accuracy of the equipment, signal interference, and atmospheric conditions.