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I have noticed at a local airport the AWOS METAR oftentimes is missing visibility measurements. In talking with other more experienced pilots, they tell me this isn't an isolated thing. They indicated that they read between the lines of the other data on the report (or other reports) to get an idea of what weather to expect.

Example: KTPF 132055Z AUTO 29004KT SCT080 30/22 A2991 RMK AO2 PWINO

The recording always states "VISIBILITY MISSING" meaning it has a sensor and is just... not working?

My questions are:

  1. Is it really normal to see reports without viz?
  2. Why does this happen so often for AWOS when ATIS doesn't have problems with it?
  3. Should this be reported to some entity (NOAA/FAA) to get these systems repaired or exchanged?
  4. The fact that it is missing visibility information does not mean that visibility is unobstructed, right? I have heard people assume this.
  5. If the recording says "VISIBILITY MISSING", is it indicated in the METAR somewhere?
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  • $\begingroup$ PWINO indicates the present weather indicator is INOP. Not sure if visibility is rolled into that or not. $\endgroup$ – casey Oct 14 '15 at 16:44
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My questions are:

Is it really normal to see reports without viz?

Yes! Well, maybe not "normal", but it does happen. Automated weather stations are like another piece of equipment and components fail from time to time, including the components which measure the visibility. The other components also fail from time to time (I've see ASOS/AWOS reports without temperature, barometric pressure, etc.)

Why does this happen so often for AWOS when ATIS doesn't have problems with it?

You shouldn't see this at all with ATIS, because a human is involved, and if the equipment which measures visibility is inoperative, a trained observer (often the same person that is manually recording the ATIS) can look out the window and record the visibility themselves.

Should this be reported to some entity (NOAA/FAA) to get these systems repaired or exchanged?

I would let the airport manager know just in case they weren't aware. They are responsible for notifying the FAA.

The fact that it is missing visibility information does not mean that visibility is unobstructed, right? I have heard people assume this.

If the visibility is missing, it means just that. It is missing. It might be 1/4 SM or it might be 20 SM. Some people may make assumptions that if there is no precipitation, that the temperature / dew point spread is high, etc. that the visibility is good, but that is a potentially dangerous assumption because visibility can be influenced by many different things. There could even be a dust storm coming through when everything else looks good!

If the recording says "VISIBILITY MISSING", is it indicated in the metar somewhere?

Sort of. It's just "missing" (i.e. the entire wind block from the METAR will not be there), so if you don't see it then, well, it's missing.

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  • $\begingroup$ Thanks for your answer! I have also noticed the wind measurements are oftentimes way off for automated stations. Is this just a fact of life with AWOS systems or am I just encountering crappy sensors!? $\endgroup$ – Charlie Oct 15 '15 at 11:41
  • $\begingroup$ @Charlie Well, sometimes it depends on the installation (I have seen stations that are never accurate if the wind is coming from the West where the trees are, etc.), and sometimes the winds are variable so it is hard to be accurate. Other times they are just crappy, lol. $\endgroup$ – Lnafziger Oct 15 '15 at 18:59

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