From: ak336@cleveland.Freenet.Edu (John Dill) Date: 12 Jan 95 01:56:05 References: 1 2
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>The fact that the aircraft's altimeter had been set in Amsterdam is >not relevant, since it had spent time flying above the transition >level. This varies from country to country, but above this altitude >all altimeters are set to standard pressure (29.92"Hg or equivalent >metric settings). A more likely problem would in fact be a confusion >as to whether the altimeter setting received from ATS was in >millibars or inches; several accidents and incidents have been traced >to this problem. Another possibility: The local altimeter setting given to the crew by ATC was either mis- understood or not accurate. In a center (where I work) altimeter setting updates are given to us only once an hour, and during periods of rapidly changing pressures (quickly moving weather systems) it's possible for the setting we give to crews to be off by several points. A change of .10 inches is equal to 100' in altitude. John -- "Negative Ghostrider, the pattern is full!"