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Old 09-12-2008, 07:14 AM   #1 (permalink)
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Default TAF covers radius of 5mi. How about...

When airport reports ceiling of xxxft, temperature, etc? How many miles radius are they talking about here? and referenced to what point of airport?

I guess another way of asking is, how many miles radius do ATIS, AWOS, etc cover and from what referenced point from aiport?

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Old 09-12-2008, 08:50 AM   #2 (permalink)
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ATIS is based on the METAR, with extra local info added. METARs are created by the Wx people and are based on either automated reports (non-towered, see below) or on tower controller reports. If a human observer is involved, assume that they will apply some common sense. There is no set radius, and some METARS are generated at non-airport locations (they are used for puropses in addition to aviation). My home patch is near the coast and the marine layer frequently parks about 500 off the end of the active...they will call that CAVU because the layer is not yet over the field and will not affect landing legalities. Based on this, I would assume that ATIS covers the airport property only

AWOS/ASOS pretty much looks straight up, and it can be 100% wrong if there is a single cloud parked over the sensor, or worse if there is a little hole in the deck right over the sensor.
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Old 09-14-2008, 03:30 PM   #3 (permalink)
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Quote:
Originally Posted by rickair7777 View Post
AWOS/ASOS pretty much looks straight up, and it can be 100% wrong if there is a single cloud parked over the sensor, or worse if there is a little hole in the deck right over the sensor.
Not to mention that a bird could land on it, nature calls, and suddenly your clear skies and 10 miles of vis drops drastically down to 100 overcast and 1/4 mi visibility.
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Old 09-14-2008, 05:53 PM   #4 (permalink)
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The temperature is taken 4 feet off the ground. An AWOS/ASOS averages what it sees straight up over a period of time to work out ceilings and cloud cover. A human observer looks at the "celestial dome," the entire sky horizon to horizon. For shooting an approach the report is for the whole airport but if you get picky, if you move a foot over, things may not be the same.
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