When are winds given with respect to true vs. magnetic north?

jrdioko
  • When are winds given with respect to true vs. magnetic north? jrdioko

    Wind information can be reported by various sources (ATIS, METAR, TAF, spoken on the radio, etc). I was taught that officially some of these sources are relative to magnetic north and others to true north (although practically this isn't always followed). Which sources are supposed to use which reference system?

  • The general rule is:

    If you read it, it's true. If you hear it, it's magnetic.

    All charts and textual sources (METAR, TAF, winds aloft, surface analysis charts, etc) use true north as the reference.

    ATIS/AWOS/ASOS or any information a controller gives you over the radio is magnetic.

    One exception to the "if you hear it" rule is that a FSS briefer will read you the winds referenced to true north, since they're just reading you the charts/textual information.

    (This is at least true in the United States... other countries may vary in some instances)

  • Another good general rule

    Everything the weather man tells you it's true ... the rest is magnetic

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