FAA Instrument Flight Instructor (FII)Instruments and SystemsHard
A pilot performs a dual VOR receiver accuracy check by tuning both navigation receivers to the same VOR station while on the ground. According to 14 CFR 91.171, the maximum permissible difference between the two indicated bearings is
- A2 degrees
- B4 degrees
- C8 degrees
- D6 degrees
Show answer & explanationAnswer & explanation
Correct answer: B. 4 degrees
Per 14 CFR 91.171, when checking one VOR receiver against another by tuning both to the same VOR facility, the maximum allowable bearing difference between the two receivers is 4 degrees. This differs from the ±4° tolerance for a ground or VOT checkpoint and the ±6° tolerance for a designated airborne checkpoint.
Why the other options are wrong
- A. 2 degrees is not one of the published tolerances for any VOR accuracy check.
- C. 8 degrees exceeds all published tolerances for any VOR check method.
- D. 6 degrees is the tolerance for a designated airborne checkpoint, not a dual receiver check.
VOR Accuracy Check (91.171)
14 CFR 91.171 requires VOR receivers used for IFR to be checked for accuracy within specified tolerances using a VOT, ground checkpoint, airborne checkpoint, or dual receiver comparison.
- VOT or ground checkpoint tolerance: ±4°
- Airborne checkpoint tolerance: ±6°
- Dual VOR receiver check: maximum 4° difference between receivers
- Checks must be logged with date, place, bearing error, and signature
Memory trick: VOT and ground: 4, sky-high: 6, dueling dials: 4.