Altimeter Question

terry wrote:


I wasnt aware you dont use the QNH term in the States. So what do you
call the number you dial up to make the altimeter read airport
elevation?

altimeter

On Apr 17, 9:40*am, Gig 601Xl Builder
wrote:
terry wrote:

I wasnt aware you dont use the QNH term in the States. *So what do you
call the number you dial up to make the altimeter read airport
elevation?

altimeter

The Department of Defense uses QNH for altimeter settings in its
forecasts; that replaced ALSTG when the old FT forecast code was
superseded by the TAF code in the late 1970's. Here's the latest TAF
for Offutt AFB:

KOFF 171410 36015G25KT 4800 -RA OVC040 QNH2996INS
TEMPO 1417 35015G35KT 3200 -TSRA OVC025CB
BECMG 1617 03015G25KT 4800 -RA BKN020 OVC040 QNH2997INS
BECMG 0203 36012G18KT 8000 -RA OVC008 QNH2985INS T10/21Z T06/14Z
1415

On Apr 18, 2:40*am, Gig 601Xl Builder
wrote:
terry wrote:

I wasnt aware you dont use the QNH term in the States. *So what do you
call the number you dial up to make the altimeter read airport
elevation?

altimeter

Nope. If you dial up the local barometric pressure the altimeter may
not read airfield elevation....

Cheers

WingFlaps wrote:
On Apr 18, 2:40 am, Gig 601Xl Builder
wrote:
terry wrote:

I wasnt aware you dont use the QNH term in the States. So what do you
call the number you dial up to make the altimeter read airport
elevation?
altimeter

Nope. If you dial up the local barometric pressure the altimeter may
not read airfield elevation....

Cheers

GO away no fly boy.

On Apr 18, 4:06*am, Gig 601Xl Builder
wrote:
WingFlaps wrote:
On Apr 18, 2:40 am, Gig 601Xl Builder
wrote:
terry wrote:

I wasnt aware you dont use the QNH term in the States. *So what do you
call the number you dial up to make the altimeter read airport
elevation?
altimeter

Nope. If you dial up the local barometric pressure the altimeter may
not read airfield elevation....

Cheers

GO away no fly boy.

I see you don't know. In fact an altimeter is calibrated to the
standard atmosphere so if the temp. is not standard it will not read
field elevation when local QNH is applied.

Pretty basic knowlege for a PPL, Oh I forgot, I'm not supposed to be a
pilot.

Cheers

WingFlaps schrieb:

I see you don't know. In fact an altimeter is calibrated to the
standard atmosphere so if the temp. is not standard it will not read
field elevation when local QNH is applied.

Wrong.

From The ICAO Manual of Radiotelephony (ICAO Document 9432) Glossary:
QNH: Altimeter sub-scale setting to obtain elevation when on the ground

So an altimeter set to local QNH will always read field elevation *by
definition*.

Pretty basic knowlege for a PPL

Indeed.

On Apr 18, 4:43*am, Stefan wrote:
WingFlaps schrieb:

I see you don't know. In fact an altimeter is calibrated to the
standard atmosphere so if the temp. is not standard it will not read
field elevation when local QNH is applied.

Wrong.

*From The ICAO Manual of Radiotelephony (ICAO Document 9432) Glossary:
QNH: Altimeter sub-scale setting to obtain elevation when on the ground

So an altimeter set to local QNH will always read field elevation *by
definition*.

* Pretty basic knowlege for a PPL

Indeed.

Yes it may say that but it's being loose because it forgt to include
the "barometric pressure reduced to MSL by application of the ISA".
Alltimeters are calibrated for the standard atmosphere. -right?
Think about it, if an ARFOR gives QNH how could it be correct for all
terrain if local temperatures differed? I covered this in my PPL tech
course -was this not covered in your manuals?
just in case you still don't see it, from Wiki:

"The altimeter is calibrated to show the pressure directly as an
altitude above mean sea level, in accordance with a mathematical model
defined by the International Standard Atmosphere (ISA)... An altimeter
cannot, however, be adjusted for variations in air temperature.
Differences in temperature from the ISA model will, therefore, cause
errors in indicated altitude."

OK?

Cheers

WingFlaps schrieb:

So an altimeter set to local QNH will always read field elevation *by
definition*.

Yes it may say that but it's being loose because it forgt to include
the "barometric pressure reduced to MSL by application of the ISA".
Alltimeters are calibrated for the standard atmosphere. -right?

Right.

Think about it, if an ARFOR gives QNH how could it be correct for all
terrain if local temperatures differed? I covered this in my PPL tech
course -was this not covered in your manuals?

Think about it, nobody said it would be correct for all altitudes, but
just for one altitude: the airfield elevation.

just in case you still don't see it, from Wiki:

Wiki, the ultimate authoritative source.

Hint: Look up the difference between QNH and QFF.

Stefan wrote in news:680f0$48077e23$54497f6b
:

WingFlaps schrieb:

I see you don't know. In fact an altimeter is calibrated to the
standard atmosphere so if the temp. is not standard it will not read
field elevation when local QNH is applied.

Wrong.

From The ICAO Manual of Radiotelephony (ICAO Document 9432) Glossary:
QNH: Altimeter sub-scale setting to obtain elevation when on the
ground

So an altimeter set to local QNH will always read field elevation *by
definition*.


No, it will read the elevation where you are. UIt will read field
elevation at the reference point.


Pretty basic knowlege for a PPL

Indeed.


Indeed indeed.


Bertie