why high to low, look out below?

"jim rosinski" wrote in message
news:uRwdf.2687$Mr4.335@trnddc08...
[...] Good GOD man, when you see the phrase "high to low, look out below"
in an aviation book they mean high to low PRESSURE.

Funny how those who are most strident and insulting also tend to be the most
ignorant as well. I wonder why that is...

Regardless of what you may think, the phrase is applied to both the pressure
situation as well as the temperature situation.

[...]
BTW, the moral of the whole "high to low (pressure), look out below" thing
is to make sure on a cross-country or IFR flight to get altimeter setting
updates regularly.

That's certainly one moral. However, getting a fresh altimeter setting
isn't going to help you correct for temperature errors. Best you know about
those as well.

Pete

Matt Whiting wrote:

http://math.isu.edu/~wolperj/cold.html

Do you want to admit now that you are wrong or keep arguing? :-)

Well if someone, somewhere, says something on the web then it *must* be
true :-) Actually the web page you cite is a good one and I recommend
folks read it. I never claimed that temperature effects don't exist.
Only that the "high to low, look out below" phrase in piloting texts
generally refers to pressure effects, not temperature effects. That's
the only sense in which I disagree with the cited article.

Here's what Jeppeson's Instrument and Commercial textbook (2003 edition)
has to say on the subject (page 2-20 on Altimeter Setting):

"The most common altimeter error is also the easiest to correct. It
occurs when you fail to keep the altimeter set to the local altimeter
setting. When flying from an area of high pressure to an area of low
pressure without resetting your altimeter, the instrument interprets the
lower pressure as a higher altitude. Since you will lower the nose of
the airplane to maintain the same indicated altitude, you will end up at
a lower true altitude. This is why, when flying from high to low
pressure, look out below."

Jim Rosinski

"jim rosinski" wrote in message
news:ZGzdf.6037$5R4.4086@trnddc06...
[...]
Only that the "high to low, look out below" phrase in piloting texts
generally refers to pressure effects, not temperature effects. That's the
only sense in which I disagree with the cited article.

Here's what Jeppeson's Instrument and Commercial textbook (2003 edition)
has to say on the subject (page 2-20 on Altimeter Setting):

Nothing about that quoted text suggests that the mnemonic is ONLY used for
that kind of error. Got anything else?

jim rosinski wrote:
[...] I never claimed that temperature effects don't exist.
Only that the "high to low, look out below" phrase in piloting texts
generally refers to pressure effects, not temperature effects. That's
the only sense in which I disagree with the cited article.

In texts that avoid going in-depth, you're right that they ignore the
temperature effect. But other references use it for both meanings, and
it's knowledge worth having.

Type the phrase into Google, and you'll find many sites, including AOPA
and at least one aviation mnemonic collection, that use it for both
pressure and temperature. A lot of us learned it that way, too.

I thought Mr Duniho did an excellent job of explaining both effects to
the OP.

Kev

"jim rosinski" wrote\ Here's what Jeppeson's
Instrument and Commercial textbook (2003 edition)
has to say on the subject (page 2-20 on Altimeter Setting):

"The most common altimeter error is also the easiest to correct. It
occurs when you fail to keep the altimeter set to the local altimeter
setting.

That's pilot error. Altimeters have accuracy errors quite independent of
that. Temperature errors are discussed in every level of ground school
training.

moo

Huh, can't you understand English?

Nothing I said had the extraneous word included, I was
saying that the errors can be additive, both pressure and
temperature work in the same way and that in mountainous
areas the errors can be greater than the indicated terrain
clearance.

The reference to IFR is just a benchmark for those who might
see MOCA as always being a safe altitude to select whether
VFR or IFR (many people use IFR charts or GPS to get "safe
altitudes" and they only work when non-standard altimeter
errors are considered.


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm



"Peter Duniho" wrote in
message ...
| "Jim Macklin" wrote
in message
| news:2Nwdf.943$QW2.628@dukeread08...
| IFR in mountainous areas requires 2,000 above obstacles
with
| 5 miles of the intended route.
|
| First, nothing in this thread limited the discussion to
IFR. Second,
| nothing in this thread limited the discussion to
mountainous terrain.
| Third, a 2000' error is barely more common as a result of
pressure
| differences than of non-standard temperature. Fourth,
nothing in your post
| suggests that temperature error is irrelevant (or
"extraneous to the
| discussion at hand", as you put it).
|
| The issues of altimeter error are introduced during
primary training for
| good reason. Altimeter error is not just an "IFR in
mountainous areas"
| problem, and it doesn't take a 2000' error to become a
problem. Just
| because one can theoretically see the terrain doesn't mean
that a) they can,
| or b) that they will still avoid the terrain. It is even
legal to not be
| able to see the terrain and still fly under VFR.
|
| The entire second half of your post is certainly no less
"extraneous to the
| discussion at hand" than my contribution, that's for sure.
For someone who
| presumes to tell me whether my contribution is
"extraneous" or not, you sure
| took off on a non-sequitur there.
|
| Pete
|
|

jim rosinski wrote:

Matt Whiting wrote:

http://math.isu.edu/~wolperj/cold.html

Do you want to admit now that you are wrong or keep arguing? :-)


Well if someone, somewhere, says something on the web then it *must* be
true :-) Actually the web page you cite is a good one and I recommend
folks read it. I never claimed that temperature effects don't exist.
Only that the "high to low, look out below" phrase in piloting texts
generally refers to pressure effects, not temperature effects. That's
the only sense in which I disagree with the cited article.

I still disagree with "generally." During my search I found at least as
many that referred to both temperature and pressure as I did that
referred to pressure alone. And since the mnemonic DOES in fact apply
equally well to both parameters, then I believe that the books that
reference pressure changes only are seriously in error.


Matt

"Jim Macklin" wrote in message
news:TgHdf.981$QW2.855@dukeread08...
Huh, can't you understand English?

I understand it just fine. Why you see the need to ask, that's unclear.

Nothing I said had the extraneous word included,

You're right...I should have written "as Rich put it".

I was
saying that the errors can be additive, both pressure and
temperature work in the same way and that in mountainous
areas the errors can be greater than the indicated terrain
clearance.

Sorry if I seemed defensive. However, I'll suggest that given that you
weren't addressing my comments in the post to which you replied, perhaps you
could have picked a more relevant post to reply to.

Pete

I accept your apology.



--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm



"Peter Duniho" wrote in
message ...
| "Jim Macklin" wrote
in message
| news:TgHdf.981$QW2.855@dukeread08...
| Huh, can't you understand English?
|
| I understand it just fine. Why you see the need to ask,
that's unclear.
|
| Nothing I said had the extraneous word included,
|
| You're right...I should have written "as Rich put it".
|
| I was
| saying that the errors can be additive, both pressure
and
| temperature work in the same way and that in mountainous
| areas the errors can be greater than the indicated
terrain
| clearance.
|
| Sorry if I seemed defensive. However, I'll suggest that
given that you
| weren't addressing my comments in the post to which you
replied, perhaps you
| could have picked a more relevant post to reply to.
|
| Pete
|
|