Correct they all fly pressure altitude and use 1013 hPa as the ISA standard.
The reason it's hPa is because it's requires no modification of the
altimeter where the original unit was millibars.
Mike Payne
----- Original Message -----
From: "STANLEY DOORE" <[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[email protected]>
Sent: Tuesday, 27 November 2007 17:09
Subject: [USMA:39802] Re: altimetry at Boeing
Don't all aircraft fly on pressure-altitude so everyone uses the same
measurement and therefore the same altitude? And, the pressure-altitude
is in metric units (kPa) or the standard atmosphere.
Stan Doore
----- Original Message -----
From: "Martin Vlietstra" <[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[email protected]>
Sent: Saturday, November 24, 2007 2:34 PM
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
