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An aircraft is on the 163° radial from VOR AAV. If the magnetic variation at the aircraft is 19°W, and the magnetic variation at the station is 21°W. What is the true bearing from VOR AAV to the aircraft?

  • A

    324°

  • B

    144°

  • C

    142°

  • D

    182°

Refer to figure.
Radial
A magnetic bearing extending from a VOR/VORTAC/TACAN. This definition gives us two key points to note.

  • Radials are referenced to Magnetic North, not True North.
  • Radials extend outward from the VOR.

Calculate the True Bearing
To convert the magnetic bearing (radial) to the true bearing from VOR AAV to the aircraft, we apply variation. Since a VOR measures bearing at the station, unlike an NDB/ADF, which measures at the aircraft, we use the variation at the station, i.e. 21°W. Therefore,

  • Magnetic Bearing to the aircraft (radial) = 163°
  • Using the mnemonic “VARIATION WEST → MAGNETIC BEST”
  • However, since we are converting from magnetic bearing to true bearing, we reverse the mnemonic.
  • True Bearing to the aircraft: 163°(M) - 21°W = 142°

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