On 2006-01-23, Martin Rowley wrote:

"Tudor Hughes" wrote in message
ups.com...
Biggin Hill has been showing temps of 3°C all day, whereas here
at Warlingham (4 miles west, same altitude) it has not got above 1.5°C
and is now (1430) down to 1.0°C. snip The visibility (2500 m) at
Biggin Hill
also looks too low (about 3 miles, 5000 m here) as does their QNH
(1033), 2 mb lower than Gatwick, Heathrow and here. snip
It doesn't give one much confidence in
METAR's and makes you wonder who actually carries out the observations.

... as you say, these differences are *very* worrying, particularly the
QNH discrepancy. I know we've moved on from the days of a forecaster &
observer working in an office and cross-checking against charts etc.,
but it does demonstrate the benefit of that system. It also implies that
the staff aren't really interested in what they are putting out - again
the QNH error would have been regarded as a cause for a minor 'flap'
with check barometers (in the days of PABAR's) being demanded in a hurry
from Bracknell etc. Obviously there is no system of double-barometer in
operation, or else, the correction tables have been erroneously set up?

Martin.



So what would be the risk to aviators of the QNH error? Is it
dangerous?

--
Jon
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