AWOS/ASOS timeliness on internet/ADS-B

RussR

RussR

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Russ
If you listen to an AWOS/ASOS on the radio, or call it on the phone, the weather is up-to-the-minute current.

However, if you bring it up in an app, or on the internet, even at aviationweather.gov, the recency of the report varies widely. These sources all get the weather through a system called WMSCR, which is what all the AWOS/ASOS systems are tied into for further dissemination.

For example, right now near where I live the weather reports are anywhere from 13-66 minutes old.

For the three towered airports nearby that have ATIS, the automated reports using ASOS are around 66 minutes old - so it seems like the dissemination might be tied to the ATIS update interval. (Although when I call on the phone, it's up to the minute - and as I type this, they all updated, right before the 55 minutes past the hour ATIS update.)
The towered airport without an ATIS (it has an AWOS) is showing 15 minutes old.
The untowered airports (with AWOS) are showing 25-30 minutes old.

Does anybody know 1) why the difference in the automated updates, and 2) why it seems to be different for different types of airports. Is it tied to the ATIS update rate for a towered field? Is the different ASOS vs AWOS, towered vs non-towered, having a change in weather worth updating, or something else?
 
I've noticed the same thing.
Some apps are 20 or more minutes behind on the weather.
 
Yep. I use Avia Weather, and the AWOS reports seem to update near the top of the hour. AWOS transmissions update every minute or two.
 
Well it seems that 98% or more of towered airports cut the wx info just shy of the hour mark unless of course any of those significant wx changes occur. Obviously they add in their own runway and other stuff. I my first CFI was ATC before becoming a pilot. He said they are required to "cut a tape" (or whatever it is in digital days) near the top of the hour - unless of course a significant wx change.

I figured the AWOS systems out there just dial into the mother ship or maybe its 3 or 4 times per hour - unless of course there is some significant wx change - but not really sure about that one for uncontrolled.

I love that the phone call is the same as listening to it live on the radio.

That why its hard to really trust any METAR in any digital form if the wx is getting real dynamic. Always seems to old enough to be frustrating rather than helpful.

I recall coming home once from out west (SD to MN) it was showing MVFR at one nearby airport and IFR at our destination and 3 other nearby airports. From the air it didn't seem that bad. I called up Flight Services weather and asked them to call our local AWOS phone number. About 30 seconds later they replied "The AWOS indicates ceilings broken 8,000...". The ADSB based METAR was still showing IFR when we landed.
 
METARs, the source of your online weather, are usually updated once per hour unless there is a significant change in weather. Just another way we are stuck in the past. With today's modern technology there is no reason we couldn't have the one minute weather available online, but good luck arguing that with the NWS. I have tried.
 
Another consideration is the update interval of the app itself (pull interval). How often does the app download the data? Cellphone radios suck power, so apps may limit data downloads. Seems that a simple in-app option should exist so the user can set the update interval.
 
Sinistar said:
....He said they are required to "cut a tape" (or whatever it is in digital days) near the top of the hour - unless of course a significant wx change....
Click to expand...
I just substitute "recording" for "tape," and then I don't have to worry about changes in recording media.
 
This issue is why I have a receiver at home, connected to an outdoor antenna and set to the ATIS frequency of my local field. Of course, that's still not up-to-the minute like an AWOS/ASOS broadcast.

I also like Web cams, where available.
 
Definitely a delay. Have you seen a AWOS machine before? I diverted to an airport before and was hanging out there and I went inside and saw the AWOS machine, it’s basically real-time and when it reads off the weather it goes by what it is at that moment. Constantly changing (but still somewhat in the ballpark). By the time it gets to the internet who knows what dataset it’s using.
 
mandm said:
Definitely a delay. Have you seen a AWOS machine before? I diverted to an airport before and was hanging out there and I went inside and saw the AWOS machine, it’s basically real-time and when it reads off the weather it goes by what it is at that moment. Constantly changing (but still somewhat in the ballpark). By the time it gets to the internet who knows what dataset it’s using.
Click to expand...

The AWOS/ASOS is constantly reporting. However the METAR data is only updated hourly. It would really be a matter changing a setting in the NWS system to update METAR data faster, they just won't do it. It is just another hold over from the old teletype days, just like NOTAMs.
 
midwestpa24 said:
The AWOS/ASOS is constantly reporting. However the METAR data is only updated hourly. It would really be a matter changing a setting in the NWS system to update METAR data faster, they just won't do it. It is just another hold over from the old teletype days, just like NOTAMs.
Click to expand...

METARs are updated before the normal time if there is a change significant enough to warrant it.
 
Palmpilot said:
This issue is why I have a receiver at home, connected to an outdoor antenna and set to the ATIS frequency of my local field.
Click to expand...
Your field's ATIS doesn't have a phone number?
 
midwestpa24 said:
However the METAR data is only updated hourly.
Click to expand...
Palmpilot said:
METARs are updated before the normal time if there is a change significant enough to warrant it.
Click to expand...

Neither of these seem to be quite right.

From aviationweather.gov, here are the recent METARS for HSD, which has an AWOS:

KHSD 181935Z AUTO 18016G21KT 10SM 32/11 A2995 RMK A01
KHSD 181915Z AUTO 20014KT 10SM 32/11 A2996 RMK A01
KHSD 181855Z AUTO 20014G19KT 10SM 32/11 A2997 RMK A01
KHSD 181835Z AUTO 20011G18KT 10SM 32/11 A2998 RMK A01

So, every 20 minutes. These do seem to coincide with the reports available on Foreflight and other sources.

Same for RCE with an AWOS, in fact even the same times:
KRCE 181935Z AUTO 21013KT 9SM 32/11 RMK AO2 TSNO
KRCE 181915Z AUTO 23014G21KT 10SM 31/11 RMK AO2 TSNO
KRCE 181855Z AUTO 20014KT 9SM 31/10 RMK AO2 TSNO
KRCE 181835Z AUTO 21011G22KT 10SM 31/11 RMK AO2 TSNO

For OUN, which is towered by does not have an ATIS, the AWOS is updated hourly:
KOUN 181945Z 18012G16KT 10SM CLR 32/10 A2995
KOUN 181845Z 14013G16KT 10SM CLR 32/09 A2998
KOUN 181745Z 20015G19KT 10SM CLR 32/11 A3001

For OKC, which is towered and has an ATIS, the ASOS is also every hour:
KOKC 181852Z 19012G18KT 10SM FEW200 31/11 A2999 RMK AO2 SLP140 T03110111
KOKC 181752Z 21015G21KT 10SM FEW200 31/12 A3001 RMK AO2 SLP148 T03060117 10306 20144 58016
KOKC 181652Z 19014G22KT 10SM FEW250 29/12 A3004 RMK AO2 PK WND 19026/1627 SLP158 T02940122

But for GOK which is untowered and has an ASOS, it's only every hour:
KGOK 181753Z AUTO 20015G22KT 10SM CLR 32/12 A2998 RMK AO2 SLP142 T03170117 10317 20139 58014
KGOK 181653Z AUTO 20014G18KT 10SM CLR 31/12 A3000 RMK AO2 SLP150 T03060117
KGOK 181553Z AUTO 20013G22KT 10SM CLR 28/12 A3002 RMK AO2 SLP156 T02830117

So I don't see a consistent rule here. We have AWOS that is every 20 minutes, and AWOS that is every hour. We have towered fields every hour regardless of AWOS or ASOS. We have untowered fields that are every 20 minutes, and one that is every hour.

The only connection I see is that ASOS seems to be every hour, where AWOS is either every hour or every 20 minutes, from my limited sample. I did check a few others, but see no pattern.
 
asicer said:
Your field's ATIS doesn't have a phone number?
Click to expand...
If I happen to be near the radio, it's one or two knob twists vs. a bunch of keystrokes to use the phone.
 
RussR said:
Neither of these seem to be quite right.

From aviationweather.gov, here are the recent METARS for HSD, which has an AWOS:

KHSD 181935Z AUTO 18016G21KT 10SM 32/11 A2995 RMK A01
KHSD 181915Z AUTO 20014KT 10SM 32/11 A2996 RMK A01
KHSD 181855Z AUTO 20014G19KT 10SM 32/11 A2997 RMK A01
KHSD 181835Z AUTO 20011G18KT 10SM 32/11 A2998 RMK A01

So, every 20 minutes. These do seem to coincide with the reports available on Foreflight and other sources.

Same for RCE with an AWOS, in fact even the same times:
KRCE 181935Z AUTO 21013KT 9SM 32/11 RMK AO2 TSNO
KRCE 181915Z AUTO 23014G21KT 10SM 31/11 RMK AO2 TSNO
KRCE 181855Z AUTO 20014KT 9SM 31/10 RMK AO2 TSNO
KRCE 181835Z AUTO 21011G22KT 10SM 31/11 RMK AO2 TSNO

For OUN, which is towered by does not have an ATIS, the AWOS is updated hourly:
KOUN 181945Z 18012G16KT 10SM CLR 32/10 A2995
KOUN 181845Z 14013G16KT 10SM CLR 32/09 A2998
KOUN 181745Z 20015G19KT 10SM CLR 32/11 A3001

For OKC, which is towered and has an ATIS, the ASOS is also every hour:
KOKC 181852Z 19012G18KT 10SM FEW200 31/11 A2999 RMK AO2 SLP140 T03110111
KOKC 181752Z 21015G21KT 10SM FEW200 31/12 A3001 RMK AO2 SLP148 T03060117 10306 20144 58016
KOKC 181652Z 19014G22KT 10SM FEW250 29/12 A3004 RMK AO2 PK WND 19026/1627 SLP158 T02940122

But for GOK which is untowered and has an ASOS, it's only every hour:
KGOK 181753Z AUTO 20015G22KT 10SM CLR 32/12 A2998 RMK AO2 SLP142 T03170117 10317 20139 58014
KGOK 181653Z AUTO 20014G18KT 10SM CLR 31/12 A3000 RMK AO2 SLP150 T03060117
KGOK 181553Z AUTO 20013G22KT 10SM CLR 28/12 A3002 RMK AO2 SLP156 T02830117

So I don't see a consistent rule here. We have AWOS that is every 20 minutes, and AWOS that is every hour. We have towered fields every hour regardless of AWOS or ASOS. We have untowered fields that are every 20 minutes, and one that is every hour.

The only connection I see is that ASOS seems to be every hour, where AWOS is either every hour or every 20 minutes, from my limited sample. I did check a few others, but see no pattern.
Click to expand...
I have seen towers issue special observations between the normal METAR times. Haven't you?
 
It sound like what they need to do is set them up to take 5 minute observations, but only publish online if there is a change of X in a given parameter.

And X may be variable. Change in ceiling from 500 to 600 needs to be published, but change from 4000 to 4500 can wait.
 
That is just a matter of tweaking the parameters.
 
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