Altimeter Calibration Height

Recently, Steven P. McNicoll posted:

"Neil Gould" wrote in message
et...

I think the issue is with your use of the term "indicates altitude",
which should be "senses pressure".


It's not an issue with me. Altimeters indicate altitude by sensing
pressure.

Correct, however the "indication" (display) is not the *method* (sensing
pressure). So, your assertion: "In other words, an altimeter indicates
altitude at the level of the instrument itself." is only valid under a few
specific circumstances.

[...] Consider that when you tell a pilot that the "altimeter is
30.12", the pilot adjusts the _indicated altitude_ by setting the
Kollsman window to that _pressure setting_.


When you tell a pilot "altimeter 3012" the pilot simply adjusts the
Kollsman setting to 3012.

Do you see a difference between my statement and yours, other than the
decimal point?

Neil

"Neil Gould" wrote in message
t...

Correct, however the "indication" (display) is not the *method* (sensing
pressure).


Who said it was?



So, your assertion: "In other words, an altimeter indicates
altitude at the level of the instrument itself." is only valid under a few
specific circumstances.


What would those few specific circumstances be?



Do you see a difference between my statement and yours, other than the
decimal point?


Yes. You say the pilot adjusts the indicated altitude, I say he adjusts the
altimeter setting.

Recently, Steven P. McNicoll posted:

"Neil Gould" wrote in message
t...

Correct, however the "indication" (display) is not the *method*
(sensing pressure).


Who said it was?

You do when you imply that there is a necessary agreement between what the
altimeter senses and what it displays.

So, your assertion: "In other words, an altimeter indicates
altitude at the level of the instrument itself." is only valid under
a few specific circumstances.


What would those few specific circumstances be?

Jose listed them in response to an earlier post of yours.

Do you see a difference between my statement and yours, other than
the decimal point?


Yes. You say the pilot adjusts the indicated altitude, I say he
adjusts the altimeter setting.

You actually said, "When you tell a pilot "altimeter 3012" the pilot
simply adjusts the *Kollsman
setting* to 3012." (emphasis mine). As we described the same action, this
distinction is without a functional difference.

Neil

"Neil Gould" wrote in message
t...

You do when you imply that there is a necessary agreement between what the
altimeter senses and what it displays.


What implied that?



Jose listed them in response to an earlier post of yours.


I must have missed that one.



You actually said, "When you tell a pilot "altimeter 3012" the pilot
simply adjusts the *Kollsman setting* to 3012." (emphasis mine).
As we described the same action, this distinction is without a functional
difference.


I think there's a significant functional difference between adjusting the
altimeter setting and adjusting the indicated altitude.

Recently, Steven P. McNicoll posted:

"Neil Gould" wrote in message
t...

You do when you imply that there is a necessary agreement between
what the altimeter senses and what it displays.


What implied that?

On 4/2/07, you wrote:
"An altimeter indicates altitude at the level of the instrument itself. "

and, again:
"In other words, an altimeter indicates altitude at the level of the
instrument itself. "

And so forth. That is not necessarily so.

You actually said, "When you tell a pilot "altimeter 3012" the pilot
simply adjusts the *Kollsman setting* to 3012." (emphasis mine).
As we described the same action, this distinction is without a
functional difference.


I think there's a significant functional difference between adjusting
the altimeter setting and adjusting the indicated altitude.

Well, I wrote:
"Consider that when you tell a pilot that the "altimeter is 30.12", the
pilot adjusts the indicated altitude by setting the Kollsman window to
that pressure setting."

The "adjustment" in both cases is to the Kollsman setting. The result is a
change in the displayed altitude. So, what is different is the structure
of the sentence, not the action or intent, unless you think your omission
of the resulting displayed altitude is significant. If so, why do you
think so?

Neil

"Neil Gould" wrote in message
. net...

On 4/2/07, you wrote:
"An altimeter indicates altitude at the level of the instrument itself. "

and, again:
"In other words, an altimeter indicates altitude at the level of the
instrument itself. "

And so forth. That is not necessarily so.


Why not?

Recently, Steven P. McNicoll posted:

"Neil Gould" wrote in message
. net...

On 4/2/07, you wrote:
"An altimeter indicates altitude at the level of the instrument
itself. "

and, again:
"In other words, an altimeter indicates altitude at the level of the
instrument itself. "

And so forth. That is not necessarily so.


Why not?

After puzzling the difficulties that several of us have had in trying to
explain the differences between "indicated" (e.g. what the pilot sees) --
and "senses" (how the altimeter is calibrated), I can only guess that for
you, sitting in the tower, there is no practical difference because you
are always at the same altitude. ;-) You can review some of the
excellent explanations that Jose and others have provided to answer your
question.

The original question asked whether the altimeter is set to indicate the
altitude at the wheels or "at the level...",
and if that question has been definitively answered, I missed it.

Neil