What does tendency of RVR (Runway Visual Range) mean and why down and up have the same values?
This is from AWOS(Automated Weather Observing System)
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1$\begingroup$ that same value for up and down must be a typo! $\endgroup$– Jamiec ♦Commented Nov 18, 2021 at 12:22
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4$\begingroup$ can you provide a link to the document you extracted the table from? $\endgroup$– FedericoCommented Nov 18, 2021 at 12:36
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1 Answer
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When included as part of the RVR, the tendency indicates whether it is trending up (improving), down (deteriorating) or there is no change. It is usually indicated by the suffix U or D.
When reported in a METAR it means that in the 10 minutes preceeding the observation, the mean RVR in the first 5 minutes varied from the mean RVR is the second 5 minutes by 100m or more.
An example would be R12/P1200U
- Runway 12
- Greater than 1200m
- Improving
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$\begingroup$ Thanks @mins I was really struggling to find something that matched my knowledge $\endgroup$– Jamiec ♦Commented Nov 18, 2021 at 12:45
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$\begingroup$ Thank you for your answer. Considering Metar, you're right. The message type in my case is awos not metar. So if the tendency value is 1 it means a tendecy exists, if 0 it means a tendency doesn't exist. $\endgroup$– mkaCommented Nov 18, 2021 at 13:06
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$\begingroup$ @mins that's the one I found, but as it was Chinese I wasnt sure it was a very good (ICAO) reference. $\endgroup$– Jamiec ♦Commented Nov 18, 2021 at 14:06