Unless you have worked in or near FAA systems, you can't imagine how long systems survive. It is possible that the implementation of ADS-B will change this situation but I don't know just how altitude for ADS-B will be derived. This system is expected to be in full service in about 2020 but I won't hold my breath.
m. f. moon ------ Original Message ------ Received: Sat, 24 Nov 2007 11:40:40 AM PST From: "Martin Vlietstra" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[email protected]> Subject: [USMA:39759] Re: altimetry at Boeing One has to weigh up the cost of a conversion from barometric to GPS altitude. It would have to be done overnight as all the aircraft "highways" are determined by altitude. This would mean that all aircraft would have to be equipped with both types of device. It is probably a matter of "If it ain't broke, don't fix it". -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bill Potts Sent: 23 November 2007 21:21 To: U.S. Metric Association Subject: [USMA:39757] Re: altimetry at Boeing Any time in the future? That's pretty pessimistic. Surely you mean "any time in the foreseeable future." I can't imagine barometric pressure being the basis fifty years from now, for example. Bill -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of m. f. moon Sent: Friday, November 23, 2007 09:36 To: U.S. Metric Association Subject: [USMA:39756] Re: altimetry at Boeing The "GPS" standard for aviation navigation is the WAAS or wide area augmentation system. In this system, only two-dimensional positions are derived from the GPS signals -- latitude and lognitude based on the WGS-84 datum. All altitude is derived from the barometric altimeter. There is no provision for GPS derived elevation or altitude. This is not likely to change any time in the future. I was closely involved in the development of the ground and aircraft interface of the WAAS the last few years I worked. M. F. Moon ------ Original Message ------ Received: Wed, 21 Nov 2007 07:14:31 AM PST From: "Michael Payne" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[email protected]>Cc: <[EMAIL PROTECTED]>, "Gordon, Trey" <[EMAIL PROTECTED]> Subject: [USMA:39737] Re: altimetry at Boeing There is no Aviation standard of Statute Miles, it's entirely a US standard for visibility, everyone else uses meters, the ICAO standard is meters. This guy might be an engineer at Boeing but he's obviously not knowledgeable about international standards. Russia, Mongolia and China use meters for Altitude, everyone else uses feet or Flight Levels. Mike Payne ----- Original Message ----- >> >> the aviation industry standard for distance is nautical miles, statue >> miles, and feet (altitude). >> meter is never used (even internationally). >> >> Trey Gordon, Ph. D. >> NDE Engineer >> Boeing Phantom Works, Seattle, WA >> [....] >> >> -----Original Message----- >> From: Bossi, Richard H >> Sent: Monday, November 19, 2007 2:55 PM >> To: Gordon, Trey >> Subject: FW: [USMA:39729] Altimeters >> >> Trey, >> >> Would you happen to know the answers to the questions below? >> >> Thanks, >> >> Dick >> >> -----Original Message----- >> From: Patrick Moore [mailto:[EMAIL PROTECTED] >> Sent: Monday, November 19, 2007 12:01 PM >> To: Bossi, Richard H >> Subject: FW: [USMA:39729] Altimeters >> >> I pass along two questions on altimetry posed by one of our metric >> reviewers. Please feel free to delete this message without response >> to me. >> >> But maybe you know a designer at Boeing who could answer easily? >> >> ------ Forwarded Message >> From: <[EMAIL PROTECTED]> >> Reply-To: <[EMAIL PROTECTED]> >> Date: Mon, 19 Nov 2007 13:10:48 -0600 (CST) >> To: "U.S. Metric Association" <[email protected]> >> Subject: [USMA:39729] Altimeters >> >> Michael, >> >> Are altimeters in most aircraft (designed since year ????) now based >> on GPS data rather than on variable atmospheric pressure? >> >> And, are most of the newer GPS altimeters switchable (km and other >> than km)? >> >> Gene Mechtly. >> >> >> ------ End of Forwarded Message >> > > ------ End of Forwarded Message >
