Pilots complaining about AWS reports

[sthguy]

This morning on Morning Report Nat Rad, a segmet about airline industry reaction to the lack of manually produced METAR reports from smaller airfields in the Sth Island.
The consensus from the pilots point of view is that visibility and cloud information derived from AWS are not worth the paper they are written on. Anyone else here it?

[NZ Thunderstorm Soc]

No.
JohnGaul
NZThS

[Myself]

When you see how visibility is measured on an AWS, it does raise question marks. It's good for a general idea, but for specifics....hmmm, not sure.
Cloud information? Also a little questionable but generally not too bad. It depends on how good the algorithm is. They often don't report high cloud (which is of no significance to pilots when taking off and landing anyway).

I think both manuals and AWS' have their place. There's a richness in manual reports (eg, the RMK field), and in weather trends in SYNOPs, and the visibility and cloud information is generally very good.
AWS' are superb for tracking features.

Bear in mind also that the definition of "visibility" is up for grabs, and I think it is not always the same for pilots and meteorologists...

[Area51]

Link here, with audio link at the bottom of the article:

http://www.radionz.co.nz/news/stories/2 ... 45c7162285

[NZstorm]

Ofcoarse to get a manual metar there needs to be someone available to do it. Are these smaller airfileds manned?

[sthguy]

Probably they are refering to locations where AWS have taken over from Metars. In anycase the thrust of their point is that they beleive AWS are mis-reporting cloud and visibility wherever they are located which is dangerous and and has lead to poor decision making. I think Metars are still done at the main centre airports which possibly tells you something.

[sthguy]

Bear in mind also that the definition of "visibility" is up for grabs, and I think it is not always the same for pilots and meteorologists...

Ummm - for Aviation forecasters, I would hope that the definition is EXACTLY the same. Otherwise the system is in trouble.....

[Myself]

Bear in mind also that the definition of "visibility" is up for grabs, and I think it is not always the same for pilots and meteorologists...

Ummm - for Aviation forecasters, I would hope that the definition is EXACTLY the same. Otherwise the system is in trouble.....

There's a difference between "prevailing visibility" and "runway visual range".
I think AWS' report (or try to infer) the former. But pilots' most significant exposure to any sort of visibility is the latter.

[sthguy]

There's a difference between "prevailing visibility" and "runway visual range".
I think AWS' report (or try to infer) the former. But pilots' most significant exposure to any sort of visibility is the latter.

And the AWS situated at airfields are near the runway, yes? and are measuring vis at that point. Are you telling me that the visibilty they report may not be similar to the runway? What is the point of having them measure that parameter at all, if this is the case? The whole point of having AWS on airfields is to replace metars. I can understand why pilots and operators are not happy. There are obvious problems with 'trying to infer' visibility. Eg adjacent fog banks or showers close by. There is plenty of opportunity for error.

[Myself]

There's a difference between "prevailing visibility" and "runway visual range".
I think AWS' report (or try to infer) the former. But pilots' most significant exposure to any sort of visibility is the latter.

And the AWS situated at airfields are near the runway, yes? and are measuring vis at that point. Are you telling me that the visibilty they report may not be similar to the runway? What is the point of having them measure that parameter at all, if this is the case? The whole point of having AWS on airfields is to replace metars. I can understand why pilots and operators are not happy. There are obvious problems with 'trying to infer' visibility. Eg adjacent fog banks or showers close by. There is plenty of opportunity for error.

I'm no expert on this but I think the difference is just "how do you define visibility"? It's actually not all that straightforward, and RVR and prevailing vis may be slightly different.
Visibility sensors, if I remember correctly, are two probes spaced a certain distance apart, something like this:
http://badc.nerc.ac.uk/data/cardington/ ... ometer.jpg

There's obvious problems with trying to infer visibility from something like that, it gives a decent guide but nothing like the richness of information from an observer. The observer would in some instances quote, say, 30KM for Vis and put in the RMK field something like "Vis 8000 to S" if there is an approaching shower perhaps. You are correct in stating that you can't get this from an AWS.
I don't disagree with what the pilots say, I think the ideal situation is to have both! AWS and observer, then you really have a quality team. This already happens at all international airports across NZ, and the world, due to civil aviations guidelines.
So for NZ, I think this is: Auckland, Hamilton, Wellington, Christchurch, Dunedin and Queenstown. Any others?

[Willoughby]

^ Kaitaia, Whenuapai and Ohakea all seem to have observers overlooking the AWS reports (the latter two mainly for the air force however).

[Myself]

It seems like Kaitaia has lots of stations- that famous Hospital, airport, observatory and a NIWA one? Amazing for such a small place...