FAA Military Competency Practice Exam

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

1. Within 3° of the selected radial

2. Exactly on the selected radial

3. Within 6° of the selected radial

4. Any reading is acceptable as long as it is stable

The correct answer is: Within 6° of the selected radial

When conducting an airborne VOR check, the goal is to ensure that the VOR receiver is functioning correctly for navigation purposes. When the Course Deviation Indicator (CDI) needle is centered, it indicates that the aircraft is on a specific radial being transmitted by the VOR station. In this situation, the omnibearing selector (OBS) needs to be accurate to verify that the aircraft is indeed receiving a valid signal. The appropriate tolerance for the OBS reading during an airborne VOR check is within 6 degrees of the selected radial when the CDI is centered. This is in accordance with FAA requirements and reflects an acceptable level of accuracy due to various factors such as aircraft position, atmospheric conditions, and VOR receiver discrepancies. Therefore, a reading within 6 degrees of the selected radial confirms that the VOR is functioning properly and that the navigation signal is reliable. An exact reading on the selected radial would represent an ideal scenario but does not account for the inherent tolerances allowed in VOR checks. Similarly, within 3 degrees of the selected radial is a stricter standard not typically applied in this context. Accepting any stable reading would not ensure the accuracy necessary for navigation, thereby underscoring why the established tolerance of 6 degrees is both