FAA Private Pilot Helicopter (PRH)Navigation and AirspaceMedium
During preflight, a pilot performs a VOR receiver accuracy check using a VOR Test Facility (VOT). According to 14 CFR 91.171, what is the maximum allowable tolerance for this check?
- A±8 degrees
- B±4 degrees
- C±2 degrees
- D±6 degrees
Show answer & explanationAnswer & explanation
Correct answer: B. ±4 degrees
Per 14 CFR 91.171, a VOT check has a maximum permissible indicated bearing error of ±4 degrees. A designated ground checkpoint also allows ±4 degrees, while an airborne checkpoint allows a wider tolerance of ±6 degrees.
Why the other options are wrong
- A. ±8 degrees exceeds any allowable VOR check tolerance.
- C. ±2 degrees is tighter than the regulatory allowance for a VOT check.
- D. ±6 degrees applies to an airborne checkpoint, not a VOT.
VOR Receiver Accuracy Check
Required periodic check under 14 CFR 91.171 to ensure a VOR receiver's accuracy before flight under IFR; tolerances vary by check method.
- VOT check: ±4 degrees
- Ground checkpoint: ±4 degrees
- Airborne checkpoint: ±6 degrees
- Must be logged with date, place, bearing error, and signature
Memory trick: VOT and ground both say '4,' airborne gives you a little more slack at '6.'