Do those MP gauges ever get calibrated? If not then the readings will
probably not be very accurate.
--
Best Regards,
Mike

http://photoshow.comcast.net/mikenoel

A frog in a well does not know the great sea.
"Al G" wrote in message
...

"The Visitor" wrote in message
...
No, not trolling.

My friend is convinced that the altimeter setting, which is corrected to
sea level (?) would be incorrect to use. Also incorrect would be the Sea
Level Pressure listed at the end of a Metar as it is also corrected to
sea level. (Surface analysis maps also.) He needs the absolute station
pressure not corrected to anything. I told him to use that but he feels
he should be taking off three odd inches to come up with the actual
pressure. I told him that lapse rate is an average used in an air mass,
not at the bottom of an air mass along the ground. valid say if he
climbed a 1000 foot tower. But I say anytime you have a station pressure
of 26 to 27 inches you will be in a real hurricane. He says, sure, but
that is at sea level. And sure we all know at different elevations, the
air is thinner. Pilots are not equipped to get through this I guess as he
has found atpl pilots (me too) give him different answers.

I am now thinking he is right, but wrong to use the one inch per thousand
feet assumption as the atmosphere is rarely standard and it is really
just for altimeter callibrations. Yet this has some strange implications
for the barometer on my wall.

He has a ton of measuring equipment and I don't know why he doesn't just
get a guage for this to.

I was hoping for a met-whiz who actually knew what is done to the raw
data ("corrected to sea level")

Any how thanks for trying.

John



Denny wrote:
On Sep 12, 6:20 pm, The Visitor wrote:

Opps, meant to put this in the piloting group. Oh well, same crowd.
Sorry.



The Visitor wrote:

So I have a friend going out to Red Deer Alberta to so some industial
air flow measurements of a sort. In his calculations he must enter the
atmospheric pressure. I thought, no problem, just get it from the
metar
for Red Deer.

Red Deer is 3000 odd feet asl. If they are reporting 29.92 is the
actual
pressure some three inches lower? But that is corrected for
temperature.
Perhaps just use the pressure at the end, I think it is in Hectopascals
but is also corrected to Sea Level. What is the actual station pressure
he should use?

John- Hide quoted text -

- Show quoted text -


The volume of replies is stunning... I suspect the gang smells a
troll...
However I am full of the milk of human kindness this AM... So,here is
the answer:

Kindly purchase any version of the private pilots exam preparation
book or CD, such as that from the Kings, et. al. and all your
questions will be answered...

denny



Walk out to any aircraft with a constant speed prop. Read the Manifold
Pressure Gauge without starting the engine. At your altitude, normally
around 27".

Al G