A pilot is flying an aircraft equipped with a single VOR receiver. To ensure the VOR receiver is operating correctly before an IFR flight, which of the following is an acceptable method for an operational check?
- AUsing a designated VOR airborne checkpoint and verifying the CDI indicates the published radial with a ±4° tolerance.
- BComparing the indication of the VOR receiver with a second, independently checked VOR receiver, ensuring they are within 4° of each other.
- CTuning to a VOR test facility (VOT) and verifying the CDI indicates 180° TO or 360° FROM with a ±6° tolerance.
- DSelecting a prominent ground landmark, tuning a VOR radial passing over it, and verifying the CDI indicates the published radial with a ±6° tolerance.
Show answer & explanationAnswer & explanation
Correct answer: D. Selecting a prominent ground landmark, tuning a VOR radial passing over it, and verifying the CDI indicates the published radial with a ±6° tolerance.
FAR 91.171 outlines acceptable VOR operational checks. Using a prominent ground landmark is an airborne check method, where the aircraft is flown over the landmark, and the VOR is tuned to a radial passing over it. The tolerance for this method, like other airborne checks, is ±6 degrees. Options A and B have incorrect tolerances, and D requires a second VOR, which the scenario specifies the aircraft does not have.
Why the other options are wrong
- A. Airborne checkpoint tolerance is ±6°, not ±4°.
- B. This is a dual VOR check, which is not applicable for an aircraft with a single VOR receiver.
- C. VOT check tolerance is ±4°, not ±6°.
VOR Ground Landmark Check
An acceptable airborne VOR operational check where the aircraft is flown over a prominent ground landmark, and the VOR indication for a known radial passing over that landmark is verified with a ±6 degree tolerance.
- Type of airborne check.
- Requires a prominent ground landmark.
- Tolerance is ±6 degrees.
- Used to verify receiver accuracy.
Memory trick: VOR Checks: VOT, Ground, Air, Dual. Go for the Ground, up in the Air, or Double-check!