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datafox
31st May 2002, 23:39
1. I've never noticed a EBBR (Bruxelles) METAR with a overcast layer reported in it. I've been at EBBR many times over the last year with cloudy conditions, yet the ATIS and METAR only show several "BKN" broken layers. Why does EBBR never report a overcast layer?

2. Why use "CAVOK"? In the U.S., most large airports report cloud cover and height at any altitude, regardless of whether it is below 5,000 ft.

3. In the U.S., ASOS (Automated Surface Observing System) has been installed at many airports. Originally designed to be a stand alone-system, ASOS is a group of sensors and instruments that automatically produces METAR reports. However, during rapidly changing and/or IFR conditions ASOS frequently does not report representative conditions.

At larger airpots, ASOS is augmented by a human observer that corrects ASOS when it is missing siginificant information. However, the quality of these METAR's has diminished in the last few years as more and more observers just let ASOS handle the observation, regardless of its validity.

What type of instrumentation and observing procedures exist at Europe's larger airports?

Thanks.

Scott Voigt
1st Jun 2002, 01:40
Datafox;

Just a slight clarification. In the US all airports with an operating FAA control tower, will have an augmented ASOS. Depending on what level of service the field has, there is either a contract weather observer, a weather service observer (they are trying to get out of the business.) or a controller augmenting the observation...

regards