On Sun, 7 Mar 2004 20:42:10 -0000, "S Green"
wrote:


"Gene Nygaard" wrote in message
.. .
On Sun, 7 Mar 2004 16:18:10 +0000 (UTC), "Jukka K. Korpela"
wrote:

(Pat Norton) wrote:

Do all commercial aircraft that fly in and out of North America have
dual unit altimeters (hPa and inHg)?

I don't know about that, but as regards to the metric system, I would
like to mention that using hPa is _not_ the recommended way. Although
the "h" prefix is formally part of the SI system, it's regarded as
unsuitable by many, including NIST.

In practice, using hPa means being just _nominally_ metric, i.e. using
actually millibars but under a different name. The odd thing is that
the correct kPa would be more practical.

Amen.


What about the pieze = 1000 pascals?

The International System of Units is a meter-kilogram-second system of
units.

That mts unit of pressure is no more SI than the cgs unit of pressure,
the barye equal to 0.1 Pa.

Note that bars are so obsolete that they never did fit into any of the
many different coherent systems of units--not only do they not fit in
SI or any other coherent meter-kilogram-second system, but they did
not fit in centimeter-gram-second systems and they did not fit in
meter-ton-second systems.

Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/