The metric system is absolutely legal in the United States according to the law of 1866. I doubt whether the FAA has the right to force a pilot to use inHg for altimeter settings. Were the units used to set the altimeters really millimeters of mercury (mmHg) or were they millibars or hectopascals (these units are are the same, but hectopascal is now official). The mmHg is outdated. Everywhere else on the world altimeters are set in hectopascal. Maybe the FAA accepts hectopascals as standard units. The mmHg is a deprecated unit.
Han Historian of Dutch metrication, The Netherlands ----- Original Message ----- From: <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Saturday, 2002-03-23 16:13 Subject: [USMA:19005] mm a standard US unit? Shouldn't that be since 1866? Markus ----- Original Message ----- From: <[EMAIL PROTECTED]> To: "Metric4US" <[EMAIL PROTECTED]> Sent: Friday, March 22, 2002 9:02 PM Subject: IT JUST DOES NOT MAKE SENSE!! I have just imported 5 Small used British aircraft for operation in the USA. I am told by the FAA that the units of barometric pressure in mm of mercury used to set the altimeters are not in "standard US units of measurement". Accordingly, I have to degrade a perfectly good system of measurement of barometric pressure to meet the interpretation of Federal Aviation Regulations at a cost of nearly $2,000. The altimeters will then read in inches of Mercury. The Federal Aviation Regulations quote "All measurements are (to be)converted to standard U.S. units of measure for those instruments necessary for operation in the U.S. traffic system" Any one have a respected reference thet lists mm as a standard U.S. unit?? Heeeelp! George V Crowe
