2
$\begingroup$

Why isn't the wind in a METAR given in magnetic heading, to match the runway numbers? Especially for areas where there is a double-digit magnetic declination.

Secondary/optional question: does the ATIS broadcast in true or magnetic?

Example: BGGH 281550Z 36004KT (an airport in Greenland, var 27.55°W).

enter image description here

Source: Wikipedia (click for full image)

$\endgroup$
  • $\begingroup$ METARs are always true, regardless of magnetic variation; ATIS is always magentic (except for some automated ones I think? but I'm not 100% sure on that) $\endgroup$ – falstro Jun 28 '16 at 17:07
  • $\begingroup$ @falstro I was about to concoct a question as to why polar runways get a special treatment after reading your first comment, phew. $\endgroup$ – ymb1 Jun 28 '16 at 17:12
  • 2
    $\begingroup$ It looks to me like you're combining two different questions here. First, why do METARs use true instead of magnetic (to match runway headings, like ATIS does)? That's the case everywhere, not just in certain areas. Second, are ATIS winds still given as magnetic in (polar) regions where magnetic headings may be unreliable? If that's an accurate summary then you might consider splitting your question to get better answers on each point. $\endgroup$ – Pondlife Jun 28 '16 at 17:35
  • 1
    $\begingroup$ @mins surface winds are pretty much only used for takeoff and landing (and the ATIS is always magnetic). $\endgroup$ – falstro Jun 28 '16 at 20:40
  • 1
    $\begingroup$ @ymb1 I updated the question to just talk about METARs in general, since this is not limited to high magnetic variation (much of the US has double digit magnetic variation). Revert if you feel it's not what you're asking. $\endgroup$ – falstro Jun 28 '16 at 21:18
1
$\begingroup$

Metars are used by more groups than just aviation. In the U.S. it is official weather for the National Weather Service. It is easier to graph winds in relation to true north than have them in shown in magnetic north. The graph wouldn't make much sense.

Spoken winds are in magnetic because they are specific to aviation and that is what pilots care about.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.