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Based on the following ICAO Annex 3 criteria for the use of the abbreviation VRB (not FAA, which is different and evident):

  1. when the total variation is 60° or more and less than 180° and the wind speed is 3 kt or more, such directional variations shall be reported as the two extreme directions between which the surface wind has varied

  2. when the total variation is 60° or more and less than 180° and the wind speed is less than 3 kt, the wind direction shall be reported as variable with no mean wind direction; or

  3. when the total variation is 180° or more, the wind direction shall be reported as variable with no mean wind direction"

I bring up the following QUESTIONS

  1. Based on these criteria, is there a way to identify if a variable 2KT wind is varying less or more than 180° when the indication is just VRB02KT?

If it were varying less than 180° but at least 60° or more, would it be possible to measure its mean direction and direction range despite its low intensity of just 2KT? E.g. 15002KT 110V200.
If not, it brings me back to my first question, what is the actual variation of a VRB02KT, less or more than 180°? Could I just answer impossible to specifically tell, but it is surely 60° or higher, otherwise the mean direction would be possible to measured, even at only 2KT. E.g. 15002KT

  1. If the wind intensity following a VRB indication is 3KT or more, can I assume it is varying more than 180°? Since this excessive variation in direction (not the relatively low intensity of 3KT) is the reason why the station can't measure the mean direction precisely.

E.g. VRB03KT would mean varying by more than 180° (not 60° or more, and less than 180°) with an intensity of 3KT (which would be strong enough to provide feasible conditions for measuring the mean direction, if it wasn’t for its excessive variation in direction above 180°).

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  • $\begingroup$ It doesn't, but my question is based on these criteria, because of its inconclusiveness when considering the indication VRB02KT. I was asked this question by an instructor and neither of us could answer. $\endgroup$
    – Marcos
    Aug 29 '20 at 4:12
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    $\begingroup$ Pragmatic answer: It doesn't matter. The wind velocity is too small to have any operational impact. $\endgroup$ Aug 29 '20 at 5:16
  • $\begingroup$ I know the pragmatic answer, but some instructors don't like it. That's why I'm looking for a confirmation. Thanks for your answer! $\endgroup$
    – Marcos
    Aug 29 '20 at 5:29
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    $\begingroup$ @Marcos, The pragmatic answer is that you don’t have to worry about it because you will never hear VRB02. Instead, you will hear “winds calm” or “light and variable” if less that 3kts. In any case, the effects are inconsequential so don’t overthink things. $\endgroup$ Aug 29 '20 at 15:09
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Based on these criteria, is there a way to identify if a variable 2KT wind is varying less or more than 180° when the indication is just VRB02KT?

No, there is no way to tell. And you don't need to tell. The wind velocity is too small to have any operational impact.

If the wind intensity following a VRB indication is 3KT or more, can I assume it is varying more than 180°? Since this excessive variation in direction (not the relatively low intensity of 3KT) is the reason why the station can't measure the mean direction precisely.

Yes, that is safe to assume, as per the definition you quoted.

Remember the values you see in a METAR are average values over a period of time. If you need the immediate wind, ask the tower.

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  • $\begingroup$ Thanks for your answer. That's exactly what I thought but decided to look for a confirmation, either from experts or other pilots. $\endgroup$
    – Marcos
    Aug 29 '20 at 5:27

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