Easy ADS-B Weather Question

Do you only receive METARs and TAFs from within the ground transmitter circle you are flying in? If you are flying in Montana for example, could you see METARs in Western Washington? (I'm guessing not?)

From the pictures I've seen it looks like you can get multiple states, or maybe even nationwide radar, but I'm not sure about METARs and such.

boom3 said:

Do you only receive METARs and TAFs from within the ground transmitter circle you are flying in? If you are flying in Montana for example, could you see METARs in Western Washington. (I'm guessing not?)

From the pictures I've seen it looks like you can get multiple states, or maybe even nationwide radar, but I'm not sure about METARs and such.

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You can see METARs and TAFs for any facility that has them in the US. I used them quite a bit on the trip to OSH last week. It depends on what device you are viewing them on how easy they are to get to and view.

One of the demos I do to impress folks that haven't flown before is to pull up the map of the continental US and show them where the significant weather may be.

IIRC you get everything, except the NEXRAD radar images are at lower resolution beyond some (300nm?) distance.

It's actually a bit more complex.

There are multiple ground tower types. The METARS and TAFS are broadcast only for areas around the towers in different ways:

Surface stations broadcast:

Winds and temperature aloft within a range of 500 NM
Regional NEXRAD within a range of 150 NM
METARs, TAFs, SIGMET, and NOTAM within a range of 100 NM

Low altitude stations broadcast:

Winds and temperature aloft within a range of 500 NM
METARs, TAFs, AIRMET, SIGMET, PIREP, and SUA within a range of 250 NM
Regional NEXRAD within a range of 150 NM (no CONUS NEXRAD is broadcast from low altitude stations)
NOTAM within a range of 100 NM

Medium altitude stations broadcast:

Entire CONUS NEXRAD
Winds and temperature aloft within a range of 750 NM
METARs, TAFs, AIRMET, SIGMET, PIREP, and SUA within a range of 375 NM
Regional NEXRAD within a range of 200 NM
NOTAM within a range of 100 NM

High altitude stations broadcast:

Entire CONUS NEXRAD
Winds and temperature aloft and all 158 CONUS Class B/C airport METAR/TAF within a range of 1000 NM
AIRMET, SIGMET, PIREP, and SUA within a range of 500 NM
Regional NEXRAD within a range of 250 NM
NOTAM within a range of 100 NM

The thing to know is that once you are up in cruise, you almost always have a Medium and High altitude station in view, so you get Class B/C for 1000NM, and all METAR/TAF for 375NM.

Wow! I had no idea it was this complicated. Where would you find a map showing what station types are available where?
Perhaps the thread title should be "not so simple..."

"...METAR/TAF within 375 NM...." This is why I still like my weather to come from the satellites overhead. When I am really doing strategic planning, I like to know what is going on at my destination, and in an RV, that can be LOTS farther away than 375 NM at the start of a leg.....

The FAA does not publish the exact locations nor tower types for the various ADS-B locations.

The general idea is that the system is organized so that once you are up high enough to be going somewhere, you have coverage of a high altitude and a medium altitude tower. The real reason they have all these tower types is to optimize bandwidth use while still getting great traffic and local weather coverage down low.

So there's a technical answer that the system is complex, but the real user story is "it just works" as evidenced by the users in this thread thinking they got coverage of everything all the time.

Thanks Dynon for the information. That's a little more what I envisioned although I had no idea it was that complex.

High altitude stations broadcast:

Entire CONUS NEXRAD
Winds and temperature aloft and all 158 CONUS Class B/C airport METAR/TAF within a range of 1000 NM
AIRMET, SIGMET, PIREP, and SUA within a range of 500 NM
Regional NEXRAD within a range of 250 NM
NOTAM within a range of 100 NM

That's gotta be a fair amount of data. Any idea how often it's transmitted? Probably nothing compared to an HD Youtube video or anything but still.

The AIM actually covers all of this info. Check out Chapter 7, especially tables 7-1-1 and 7-1-2.

http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0701.html

Nothing in ADS-B is nearly as fast as any internet connection. If I remember right, a high altitude tower is about 33kbit/sec, about the speed of an old-school dial-up modem.

Ironflight said:

"...METAR/TAF within 375 NM...." This is why I still like my weather to come from the satellites overhead. When I am really doing strategic planning, I like to know what is going on at my destination, and in an RV, that can be LOTS farther away than 375 NM at the start of a leg.....

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This was a problem for me when flying back from Oshkosh this past Tuesday. I left Tulsa, OK early that morning in the RV with the plan to land back in San Jose and grab our Bonanza to run up to South Lake Tahoe (KTVL) to get my kids. I could see the satellite data for KTVL shortly after takeoff from Tulsa, but I couldn't monitor the METAR to see if the weather was improving or deteriorating. I ended up having my wife call the ASOS frequency periodically and texting me the weather until I was back in CA and could get the METAR over ADS-B. Having XM would clearly have been better.

beav said:

This was a problem for me when flying back from Oshkosh this past Tuesday. I left Tulsa, OK early that morning in the RV with the plan to land back in San Jose and grab our Bonanza to run up to South Lake Tahoe (KTVL) to get my kids. I could see the satellite data for KTVL shortly after takeoff from Tulsa, but I couldn't monitor the METAR to see if the weather was improving or deteriorating. I ended up having my wife call the ASOS frequency periodically and texting me the weather until I was back in CA and could get the METAR over ADS-B. Having XM would clearly have been better.

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I'm in no way advocating texting and flying but I'm amazed how well they go through. I wonder if there is a number you can text with an identifier that will automatically text you back the report.

There are plenty of proper ways to get weather electronically and there's always flight watch available but it could be handy at times.