ATC Altimeter Settings

"Matt Barrow" wrote in message =
...
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"John R. Copeland" wrote in message
...
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In the Rockies, there are ground stations at widely varying =
elevations.
I've guessed that ATC might not use settings from airports in deep =
valleys
for enroute settings, wherever more representative values are =
available.
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How would a station be more representative if it was/wasn't in a =
valley or
on a hill top?
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In the case of non-standard lapse rates, the lower the airport,
the more the altimeter differs from true height across mountain peaks.