Altimeter Calibration Height

Steven P. McNicoll schrieb:

You are aware that the altimeter displays the true altitude only in very
untypical, special cirumstances, are you?

Yes. I said nothing about that.

Message-ID: . net:
An altimeter indicates altitude at the level of the instrument itself.

Message-ID: nk.net:
In other words, an altimeter indicates altitude at the level of the
instrument itself.


Did you write this or was I just hearing voices?

"Stefan" wrote in message
...

Message-ID: . net:
An altimeter indicates altitude at the level of the instrument itself.

Message-ID: nk.net:
In other words, an altimeter indicates altitude at the level of the
instrument itself.


Did you write this or was I just hearing voices?


Yes, I wrote that. What is your point?

Stefan wrote in
:

Did you write this or was I just hearing voices?

Hearing voices. Nothing was said about the accuracy of the altitude
shown.


--

Steven P. McNicoll schrieb:

What is your point?

You:
An altimeter indicates altitude at the level of the instrument
itself.

Me:
Source?

You:
Logic. Where is the sensing mechanism located?


Now if the altimeter doesn't display the true altitude, your logic is
unfounded.

John Godwin schrieb:

Nothing was said about the accuracy of the altitude shown.

The question was whether the altimeter shows the altitude of the cockpit
or that of the wheels, and you say that accuracy wasn't a topic? :-))))

"Stefan" wrote in message
. ..

Now if the altimeter doesn't display the true altitude, your logic is
unfounded.


What are the voices saying to you? I said nothing about true altitude.

Think of a 200' tower situated at sea level in a standard atmosphere.
There are three identical, perfectly accurate altimeters mounted on
the tower at the 100' level, all set to 29.92. One of the altimeters is
vented directly to the atmosphere, one has a static line running to the
top of the tower, and one has a static line running to the base.

Question: What altitudes are indicated on the three altimeters?















Answer: They all indicate 100'.

The static lines are vented to the atmosphere, so the change in pressure
with altitude takes place in the static lines just as it does in the
atmosphere.
The pressure in the three altimeter cases is the same, so the indicated
altitude is the same.

Hope this helps.

Steven P. McNicoll schrieb:

The static lines are vented to the atmosphere, so the change in pressure
with altitude takes place in the static lines just as it does in the
atmosphere.
The pressure in the three altimeter cases is the same, so the indicated
altitude is the same.

Ever heard of Kollman?

"Stefan" wrote in message
. ..

Ever heard of Kollman?


No. Is there any reason I should have?

Steven P. McNicoll schrieb:

Ever heard of Kollman?

No. Is there any reason I should have?

No, not with that typo. In the kollsman window the pilot can choose what
altitude the altimeter should display. This choice may or may not be
related to the actual altitude of the airplane.

But I start to understand your reasoning: *If* the airplane sits on the
ground, and *if* the QNH tuned into the kollmans window is accurate,
*then* the altitude displayed is the altitude of the instrument itself.

But the original poster didn't specifiy any of these circumstances, and
so you didn't, either.

In other words, an altimeter indicates altitude at the level of the
instrument itself.

No. The altimeter senses pressure at the level of the instrument
itself. It indicates altitude depending on its calibration and kollsman
setting.

Jose
--
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