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VOR accuracy tolerance using a VOT

Aviation Mechanic Airframe (AMA) practice question 16 of 26 on Communications, Light Signals, and Runway Lighting Systems. ACS element AM.II.I.K9 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONA VOR receiver is operationally checked against a VOR test facility (VOT). What is the largest bearing error that still permits the aircraft to be used for IFR flight?

  1. A2 degrees
  2. B4 degrees
  3. C10 degrees
Show the answer and explanation

Correct answer: B. 4 degrees

  • A — incorrect Two degrees is tighter than the published tolerance and would reject receivers that are still within limits.
  • B — correct The handbook states an error of plus or minus 4 degrees should not be exceeded when testing a VOR system with a VOT.
  • C — incorrect An error that large is well beyond the limit; anything over 4 degrees prevents IFR use until repairs are made.

BACKGROUND

The very high frequency omni-directional range system uses VHF signals from 108 to 117.95 MHz, and functional accuracy of the airborne receiver is critical to flight safety. VOR test facilities, or VOTs, are located at numerous airports and are listed in the Airport Facilities Directory along with the specific spots on the airport surface where the test is performed. Most VOTs require tuning 108.0 MHz and centering the course deviation indicator, after which the omni bearing selector should read 0 degrees with a FROM indication or 180 degrees with a TO indication. An error of plus or minus 4 degrees may not be exceeded, and a logbook entry is required for the check.

STUDY TIP

Learn the VOT procedure as a package: 108.0 MHz, center the CDI, expect 0 degrees FROM or 180 degrees TO, tolerance 4 degrees, logbook entry required.

KEY POINTS

  • VOT checks are made by tuning 108.0 MHz and centering the CDI.
  • The indication should be 0 degrees FROM or 180 degrees TO.
  • An error greater than 4 degrees prevents IFR use until repairs are made.

SOURCES

  • FAA-H-8083-30B ch11 "VOR Navigation System"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-31B Aviation Maintenance Technician Handbook – Airframe, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.