Also - a giveaway is on some passenger planes. Those which have that handy
information screen in the screen in front of your seat. One of the info
screens is altitude and it does tend to confuse people when altitude is quoted
as far from '0' !! :-)
> Date: Sun, 18 Apr 2010 20:50:39 -0500
> From: j...@metricmethods.com
> To: usma@colostate.edu
> Subject: [USMA:47171] Re: Air flight altitudes in meters
>
>
> Thanks, John. Your knowledge obviously exceeds my faint acquaintance
> with this matter.
>
> Now, I HAVE had personal experience with aneroid altimeters, the
> pneumo-mechanical sort where the big hand spun a complete circle for
> every "one thousand feet" (I think that was the number). We used them on
> submarines to measure the "pressure in the boat". (Non-submariners
> should call 'em "ships".) Whenever we raised the induction mast to
> ventilate (an extremely infrequent event on some missions) we would
> "zero" our altimeter readout by adjusting the base pressure knob. As air
> bank pressures bled down due to air usage or rose when compressors
> charged them back up, that readout would change.
>
> Your experience undoubtedly was ABOVE sea level, though.
>
> Jim
>
> John M. Steele wrote:
> > Actually, it is nominally based on height above sealevel. Sitting on
> > the runway, with altimeter correction dialed in, it will read the
> > published height of the runway above sealevel.
> >
> > At cruise levels, no altimeter correction is used and reading is called
> > flight level. It is the height above sea level IF sea level were at 15
> > °C, 101.325 kPa, and a lapse rate of -6.5 K/km to the stratosphere (11
> > km), and zero lapse rate above that to 20 km. Further it it uses a
> > height variable called geopotential height, the height that would be
> > true if gravity were constant with height. There is a transformation
> > between that and geometric height in the standard.
> >
> > ------------------------------------------------------------------------
> > *From:* James R. Frysinger <j...@metricmethods.com>
> > *To:* U.S. Metric Association <usma@colostate.edu>
> > *Cc:* U.S. Metric Association <usma@colostate.edu>
> > *Sent:* Sun, April 18, 2010 8:47:07 PM
> > *Subject:* [USMA:47168] Re: Air flight altitudes in meters
> >
> >
> > Altimeters work off of atmospheric pressure readings, Pat. But the
> > readout is in terms of height above terrain. So assignments and reports
> > are always in length units. No human pressure to altitude correlation
> > procedures are used.
> >
> > Jim
> >
> > Pat Naughtin wrote:
> > > Dear John, Jim, and All,
> > >
> > > My understanding is that air craft actually measure pressure in
> > something like kilopascals and that this pressure measurement is then
> > changed (dumbed down ?) to a measure that implies that a measure of
> > length has been made somehow.
> > >
> > > I suppose you could dangle a mass tied on a piece of string out the
> > window of the plane so that it drags along the ground, but it sounds
> > impractical!
> > >
> > > By the way, some approximate conversions from pressure to height
> > might go something like this:
> > >
> > > Pressure
> > >
> > >
> > >
> > > Altitude
> > >
> > > kilopascal
> > >
> > >
> > >
> > > metres
> > >
> > > 100
> > >
> > >
> > >
> > > 0
> > >
> > > 90
> > >
> > >
> > >
> > > 1 000
> > >
> > > 80
> > >
> > >
> > >
> > > 2 000
> > >
> > > 70
> > >
> > >
> > >
> > > 3 000
> > >
> > > 65
> > >
> > >
> > >
> > > 4 000
> > >
> > > 60
> > >
> > >
> > >
> > > 5 000
> > >
> > > 45
> > >
> > >
> > >
> > > 6 000
> > >
> > > 40
> > >
> > >
> > >
> > > 8 000
> > >
> > > 22
> > >
> > >
> > >
> > > 10 000
> > >
> > > 19
> > >
> > >
> > >
> > > 12 000
> > >
> > > 15
> > >
> > >
> > >
> > > 14 000
> > >
> > > 10
> > >
> > >
> > >
> > > 16 000
> > >
> > > 7
> > >
> > >
> > >
> > > 18 000
> > >
> > > 4
> > >
> > >
> > >
> > > 20 000
> > >
> > > 3
> > >
> > >
> > >
> > > 25 000
> > >
> > > 1
> > >
> > >
> > >
> > > 30 000
> > >
> > >
> > > Cheers,
> > > Pat Naughtin
> > > Author of the ebook, /Metrication Leaders Guide,/ that you can obtain
> > from http://metricationmatters.com/MetricationLeadersGuideInfo.html PO
> > Box 305 Belmont 3216,
> > > Geelong, Australia
> > > Phone: 61 3 5241 2008
> > >
> > > Metric system consultant, writer, and speaker, Pat Naughtin, has
> > helped thousands of people and hundreds of companies upgrade to the
> > modern metric system smoothly, quickly, and so economically that they
> > now save thousands each year when buying, processing, or selling for
> > their businesses. Pat provides services and resources for many different
> > trades, crafts, and professions for commercial, industrial and
> > government metrication leaders in Asia, Europe, and in the USA. Pat's
> > clients include the Australian Government, Google, NASA, NIST, and the
> > metric associations of Canada, the UK, and the USA. See
> > http://www.metricationmatters.com
> > <http://www.metricationmatters.com/>for more metrication information,
> > contact Pat at pat.naugh...@metricationmatters.com
> > <mailto:pat.naugh...@metricationmatters.com>
> > <mailto:pat.naugh...@metricationmatters.com
> > <mailto:pat.naugh...@metricationmatters.com>> or to get the free
> > '/Metrication matters/' newsletter go to:
> > http://www.metricationmatters.com/newsletter to subscribe.
> > >
> > > On 2010/04/19, at 05:57 , John M. Steele wrote:
> > >
> > >> It is my understanding that European air space is controlled in feet.
> > >> The Wikipedia article on "flight level" shows a metric structure
> > for Russia, China, Mongolia, North Korea and various CIS States
> > (non-European former USSR satellites). Everybody else flies in feet (I
> > think).
> > >>
> > >> ------------------------------------------------------------------------
> > >> *From:* James R. Frysinger <j...@metricmethods.com
> > <mailto:j...@metricmethods.com> <mailto:j...@metricmethods.com
> > <mailto:j...@metricmethods.com>>>
> > >> *To:* U.S. Metric Association <usma@colostate.edu
> > <mailto:usma@colostate.edu> <mailto:usma@colostate.edu
> > <mailto:usma@colostate.edu>>>
> > >> *Sent:* Sun, April 18, 2010 3:13:10 PM
> > >> *Subject:* [USMA:47149] Air flight altitudes in meters
> > >>
> > >>
> > >> My impression had been that all air flight altitudes were given and
> > heeded in terms of feet. But this article implies flight altitudes in
> > meters.
> > >>
> > http://www.foxnews.com/world/2010/04/17/european-skies-largely-remain-fly-zone/
> > >>
> > >> Jim
> > >>
> > >> -- James R. Frysinger
> > >> 632 Stony Point Mountain Road
> > >> Doyle, TN 38559-3030
> > >>
> > >> (C) 931.212.0267
> > >> (H) 931.657.3107
> > >> (F) 931.657.3108
> > >>
> > >
> >
> > -- James R. Frysinger
> > 632 Stony Point Mountain Road
> > Doyle, TN 38559-3030
> >
> > (C) 931.212.0267
> > (H) 931.657.3107
> > (F) 931.657.3108
> >
>
> --
> James R. Frysinger
> 632 Stony Point Mountain Road
> Doyle, TN 38559-3030
>
> (C) 931.212.0267
> (H) 931.657.3107
> (F) 931.657.3108
>
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