why high to low, look out below?

[[email protected]]

i'm studying for my private license and i am a bit confused about this
high to low, look out below. the way I see it:

imagine an altimeter sitting at sea level. lets say the atomspheric
pressure at the location of the altimeter is "10" (no units, just for
simplicity). now lets say you set the altimeter to "10". so now the
altimeter reads "0 feet"

now decrease the temperature of the air surrounding the altimeter, and
since the colder air gets the more dense it gets, the atmospheric
pressure goes up. the altimeter doesnt know this. all it sees is an
increase in pressure, which it thinks means an decrease in altitude, so
it indicates say "-10 feet". this is directly contrary to the "high to
low look out below" because the altimeter is telling you you are 10
feet lower than you are, which is not what that saying is implying.

SO WHATS THE DEAL?

[Rich Lemert]

wrote:
> i'm studying for my private license and i am a bit confused about this
> high to low, look out below. the way I see it:
>
> imagine an altimeter sitting at sea level. lets say the atomspheric
> pressure at the location of the altimeter is "10" (no units, just for
> simplicity). now lets say you set the altimeter to "10". so now the
> altimeter reads "0 feet"
>
> now decrease the temperature of the air surrounding the altimeter, and
> since the colder air gets the more dense it gets, the atmospheric
> pressure goes up. the altimeter doesnt know this. all it sees is an
> increase in pressure, which it thinks means an decrease in altitude, so
> it indicates say "-10 feet". this is directly contrary to the "high to
> low look out below" because the altimeter is telling you you are 10
> feet lower than you are, which is not what that saying is implying.
>
> SO WHATS THE DEAL?
>

If I'm not mistaken, the phrase "high to low" means you are moving
from a region of higher barometric pressure to one with a lower
barometric pressure. Your altitude does not change, but because
your altimeter is seeing a lower pressure it thinks your altitude
is higher than it really is. You "think" you're at 100 ft, but you've
actually just landed.

The situation you described is more accurately referred to as "low
to high".

[George Patterson]

wrote:

> now decrease the temperature of the air surrounding the altimeter, and
> since the colder air gets the more dense it gets, the atmospheric
> pressure goes up. the altimeter doesnt know this. all it sees is an
> increase in pressure, which it thinks means an decrease in altitude, so
> it indicates say "-10 feet". this is directly contrary to the "high to
> low look out below" because the altimeter is telling you you are 10
> feet lower than you are, which is not what that saying is implying.

No, it's not contrary. The "high to low" means a flight from an area of high
pressure to low pressure, not high temperature to low temperature. When you
decreased the temperature, you increased the pressure, which means you're going
from low to high.

George Patterson
Drink is the curse of the land. It makes you quarrel with your neighbor.
It makes you shoot at your landlord. And it makes you miss him.

[City Dweller]

Hight-to-low refers BOTH to pressure and temperature, actually. An increase
in temperature causes an increase in pressure as air molecules now move
faster.

Pressure and temperature act in the same direction in terms of alimeter
settings, but work in the opposite directions in terms of aircraft
performance.

-- City Dweller

"George Patterson" > wrote in message
news:rXUcf.5372$P.3083@trndny03...
> wrote:
>
>> now decrease the temperature of the air surrounding the altimeter, and
>> since the colder air gets the more dense it gets, the atmospheric
>> pressure goes up. the altimeter doesnt know this. all it sees is an
>> increase in pressure, which it thinks means an decrease in altitude, so
>> it indicates say "-10 feet". this is directly contrary to the "high to
>> low look out below" because the altimeter is telling you you are 10
>> feet lower than you are, which is not what that saying is implying.
>
> No, it's not contrary. The "high to low" means a flight from an area of
> high pressure to low pressure, not high temperature to low temperature.
> When you decreased the temperature, you increased the pressure, which
> means you're going from low to high.
>
> George Patterson
> Drink is the curse of the land. It makes you quarrel with your
> neighbor.
> It makes you shoot at your landlord. And it makes you miss him.

[Peter Duniho]

> wrote in message
ups.com...
> [...]
> SO WHATS THE DEAL?

The deal is that this is a great example of why one needs to be very careful
about using mnemonics. They are memory devices, not physics lessons.

The phrase "high to low, look out below" applies to both temperature and
pressure, for different reasons. You have mistakenly applied the physics of
the pressure situation to a change in temperature, combining the two
situations when in fact the mnemonic really assumes that you are holding
temperature constant when you change pressure, or vice a versa.

In both cases, the issue is easier to understand if you can think about
flying at a constant pressure, rather than a constant altitude. This is, of
course, what we actually do when we fly, assuming the altimeter setting
isn't changed. All the altimeter knows is pressure, so assuming we fly at a
constant indication on the altimeter, we are flying at a constant pressure.

What this means is that as the actual pressure levels change in height, so
does the airplane. For a given barometric pressure, a higher altimeter
setting results in a greater actual height above ground. The same thing is
true for higher temperature.

You've already shown why it's true for a higher altimeter setting, but just
to review...

Your actual altitude is proportional to the difference between the
barometric pressure at your current position and the barometric pressure at
the ground below you (always higher than your current position's pressure).
If the altimeter is set with too high a setting, your indicated altitude
will be too high, and if the altimeter is set too low, the indicated
altitude will be too low. This means that if you fly from high pressure to
low, the altimeter setting will be too high, resulting in an indicated
altitude higher than actual. You can see why thinking you are higher than
you are might be bad.

In the temperature case, it's because temperature affects how quickly the
pressure actually changes with altitude. The higher the temperature, the
farther apart two given barometric pressures will be vertically. It's as if
the atmosphere is made up of layers of pressures, and higher temperature
makes those layers expand away from each other. Conversely, as the
temperature goes down, those layer get closer and more compact. Those same
two given barometric pressures wind up nearer each other vertically.

The altimeter only indicates correctly at a specific temperature. When the
temperature is higher than that, the altimeter indicates too low (because
the pressure layers have expanded apart), and when the temperature is lower
than that, the altimeter indicates too high. And of course again, an
altimeter that indicates too high is not good.

The mnemonic applies best to the pressure case, as it's easy to see how
flying from an area of high pressure to an area of low pressure might be an
issue. In addition, in the pressure case it applies mainly to the situation
when you actually change position without resetting the altimeter (so it
fits the wording of the mnemonic reasonably well).

In the case of temperature, the error exists regardless. So in that
respect, the mnemonic is misleading. It might be a useful way to remember
the issue, but it might mislead someone into thinking the hazard exists only
when one starts in an area of higher temperature and flies to an area of
lower temperature. That's not actually the case though. The real problem
is simply that the altimeter is calibrated assuming a standard atmosphere,
with a constant mapping from pressure change to altitude change when in fact
a real atmosphere varies this mapping according to temperature.

If you are flying in an area of cold air, the indicated altitude (except
right on the ground) will always be higher than your actual altitude,
assuming you're using the correct altimeter setting. It's not the act of
flying from a warmer area to a colder area, it's the act of flying in a
colder-than-standard area, period.

Hope that helps.

Pete

[Cub Driver]

On Fri, 11 Nov 2005 04:17:27 GMT, George Patterson
> wrote:

>No, it's not contrary. The "high to low" means a flight from an area of high
>pressure to low pressure, not high temperature to low temperature. When you
>decreased the temperature, you increased the pressure, which means you're going
>from low to high.

I thought at the time, and I am even more convinced today, that the
solution to all this stuff is fly VFR in daylight!

(I appreciate that this isn't a great deal of help on the written exam
or the checkflight, but the poster might keep it in mind for the
future :)


-- all the best, Dan Ford

email: usenet AT danford DOT net

Warbird's Forum: www.warbirdforum.com
Piper Cub Forum: www.pipercubforum.com
the blog: www.danford.net
In Search of Lost Time: www.readingproust.com

[Ron Natalie]

George Patterson wrote:

> No, it's not contrary. The "high to low" means a flight from an area of
> high pressure to low pressure, not high temperature to low temperature.
> When you decreased the temperature, you increased the pressure, which
> means you're going from low to high.
>
Actually Geoerge, it works for temperature as well as pressure.
Going to a colder than standard pressure causes your altimeter
to read high as well.

[Darrell S]

wrote:
> i'm studying for my private license and i am a bit confused about this
> high to low, look out below. the way I see it:
>
> imagine an altimeter sitting at sea level. lets say the atomspheric
> pressure at the location of the altimeter is "10" (no units, just for
> simplicity). now lets say you set the altimeter to "10". so now the
> altimeter reads "0 feet"
>
> now decrease the temperature of the air surrounding the altimeter, and
> since the colder air gets the more dense it gets, the atmospheric
> pressure goes up. the altimeter doesnt know this. all it sees is an
> increase in pressure, which it thinks means an decrease in altitude,
> so it indicates say "-10 feet". this is directly contrary to the
> "high to low look out below" because the altimeter is telling you you
> are 10 feet lower than you are, which is not what that saying is
> implying.
>
> SO WHATS THE DEAL?

You are arbitrarily changing the pressure due to decreased temperature. IF
that actually happens you are correct. But temperature can decrease without
increased pressure. That's why "cold or low, look out below" is correct.
If everything else stays the same except temperature drops, you will be
lower than indicated. If only the pressure drops, you will be lower than
indicted. If both decrease you will be much lower than indicated. If one
drops and the other increases, ??????,

You are overthinking the problem.

--

Darrell R. Schmidt
B-58 Hustler History: http://members.cox.net/dschmidt1/
-

[jim rosinski]

Next time a big low pressure system moves through, go sit in a plane
and check the altimeter. It should read HIGHER than the field
elevation. The altimeter is reacting to a decrease in pressure, which
it registers as an increase in altitude. Now instead of sitting on the
ground, imagine that you had *flown* from a higher pressure region to a
lower pressure region while trying to maintain a constant altitude.
You would have compensated for the (false) indication of increased
altitude (actually you were just moving from high pressure to low
pressure) by lowering the nose ever so slightly and actually *losing*
altitude. Thus "high to low, look out below".

And forget all the stuff others have posted about temperature. That
does nothing but confuse the issue.

Jim Rosinski

wrote:

> now decrease the temperature of the air surrounding the altimeter, and
> since the colder air gets the more dense it gets, the atmospheric
> pressure goes up. the altimeter doesnt know this. all it sees is an
> increase in pressure, which it thinks means an decrease in altitude, so
> it indicates say "-10 feet". this is directly contrary to the "high to
> low look out below" because the altimeter is telling you you are 10
> feet lower than you are, which is not what that saying is implying.
>
> SO WHATS THE DEAL?

[Peter Duniho]

"jim rosinski" > wrote in message
oups.com...
> And forget all the stuff others have posted about temperature. That
> does nothing but confuse the issue.

The issue is already confused. People like you who want to pretend it's not
only serve to confuse it even more.

Forget "all the stuff others have posted about temperature" at your own
peril. It's every bit as important an altimeter error as that caused by
changes in pressure.

[jim rosinski]

Peter Duniho wrote:

>>And forget all the stuff others have posted about temperature. That
>>does nothing but confuse the issue.
>
> The issue is already confused. People like you who want to pretend it's not
> only serve to confuse it even more.

"People like you" who have no lives outside of making annoying posts
that say nothing are the scourge of Usenet. To the permanent bit bucket
you go...

> Forget "all the stuff others have posted about temperature" at your own
> peril. It's every bit as important an altimeter error as that caused by
> changes in pressure.

The original question was about "high to low, look out below".
Temperature effects are completely unnecessary in forming an explanation
for that adage. What credentials do you have to back up your
blathering? On second thought, I think you'd be doing us all a favor if
instead you just went away.

Jim Rosinski

[Rich Lemert]

Peter Duniho wrote:
> "jim rosinski" > wrote in message
> oups.com...
>
>>And forget all the stuff others have posted about temperature. That
>>does nothing but confuse the issue.
>
>
> The issue is already confused. People like you who want to pretend it's not
> only serve to confuse it even more.
>
> Forget "all the stuff others have posted about temperature" at your own
> peril. It's every bit as important an altimeter error as that caused by
> changes in pressure.
>
>

While temperature may play a role in altimeter "errors" I believe
it's extraneous to the discussion at hand. The phrase in question says
nothing about why the pressure is changing, only that it does. The
effect of this pressure change on altimeter readings can - and has
been - adequately explained without discussion of temperature.

We can always discuss temperature effects once the pressure effects
are understood. Trying to get someone to grasp two separate concepts at
the same time when it's not necessary does only serve to confuse the
student.

[Andrew Sarangan]

Increase in density does not mean an increase in pressure. This is
where your error is.

[Peter Duniho]

"Rich Lemert" > wrote in message
ink.net...
> While temperature may play a role in altimeter "errors" I believe
> it's extraneous to the discussion at hand.

Why would you believe that? People can and do use that very same mnemonic
to remember the effect of temperature on the altimeter indication.

To pretend otherwise is silly. It happens, and so given that it happens, it
makes perfect sense to explain the error and why the phrase fits (albeit
imperfectly, AS I ALREADY POINTED OUT, before the post that claimed
temperature was irrelevant).

> The phrase in question says nothing about why the pressure is changing,

The phrase in question says nothing about pressure at all. The word
pressure is not even used.

> only that it does.

The only thing the phrase say that anything "does", is that the altimeter
reads too high in certain circumstances.

> The
> effect of this pressure change on altimeter readings can - and has
> been - adequately explained without discussion of temperature.

The effect of this temperature change on altimeter readings can - and has
been -adequately explained without discussion of temperature.

> We can always discuss temperature effects once the pressure effects
> are understood. Trying to get someone to grasp two separate concepts at
> the same time when it's not necessary does only serve to confuse the
> student.

As long as the exact same phrase gets used for two different concepts, you
are stuck teaching two different concepts at the same time.

Now, maybe that really means people ought to stop using the mnemonic. But
you and I have no control over it. Pretending that temperature is
irrelevant is dumb, and is likely to get someone killed.

Pete

[Peter Duniho]

"Peter Duniho" > wrote in message
...
> The effect of this temperature change on altimeter readings can - and has
> been -adequately explained without discussion of temperature.

See what copy and paste will get you?

Obviously, that last word should be "pressure".

[jim rosinski]

Andrew Sarangan wrote:

> Increase in density does not mean an increase in pressure. This is
> where your error is.

Actually it does if the air, or layer of air, you're talking about is
isothermal (constant temperature) or anything close to it. The ideal
gas law, to which the real atmosphere very nearly adheres, states:

pressure = density times temperature times a constant.

Imagine you're in freefall. Pressure goes up and density goes up. And
the above equation tells you by how much, assuming for the moment that
you have a barometer, an isothermal atmosphere, and a calculator during
the plunge!

All this is completely useless for understanding the "high to low, look
out below" rule.

Jim Rosinski

[Jim Macklin]

IFR in mountainous areas requires 2,000 above obstacles with
5 miles of the intended route. Considering that an
altimeter setting may be from a location nearly 100 miles
away and the temperature may be very much below standard,
that 2,000 foot terrain clearance may be reduced to 0 by
temperature, pressure and venturi effects in the mountains.
Try the calculations on your flight computer for true
altitude. VFR and you should see the granite, but IFR or at
night, you depend on the altimeter.
Of course, now that you can get a GPS altitude that has non
of the errors, you can see the altitude errors on the
pressure altimeter.

Altimeters have other errors besides temperature and as a
purely mechanical device they can fail with no indication at
all. The electric altimeters in the high dollars airplanes
(King Airs and jets) use an air data computer that processes
the raw pressure data and sends the result to a display.
These will flag when there is an error, but the cheap
altimeter used in most general aviation piston airplanes has
no such warning. Thirty years ago one manufacturer decide
to save a few bucks in construction and used Teflon tape for
bearings in the housing. When this tape broke loose and
jammed the gears, the altimeter would just freeze. I once
had a student out in central Illinois doing hood work on a
MVFR day. He seemed to be doing a good job as we flew
around under a 1500-2000 foot overcast. When he took the
hood off, his first remark was "How did we get so low?"
Since I'd been watching in and outside, the slow loss of
altitude did not reach the alarm stage, we were below the
clouds and above the ground. But when he went under the
hood he had a picture of what it looked like and when the
hood came off it was very different and quickly.


--
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 ...
| "Rich Lemert" > wrote in message
|
ink.net...
| > While temperature may play a role in altimeter
"errors" I believe
| > it's extraneous to the discussion at hand.
|
| Why would you believe that? People can and do use that
very same mnemonic
| to remember the effect of temperature on the altimeter
indication.
|
| To pretend otherwise is silly. It happens, and so given
that it happens, it
| makes perfect sense to explain the error and why the
phrase fits (albeit
| imperfectly, AS I ALREADY POINTED OUT, before the post
that claimed
| temperature was irrelevant).
|
| > The phrase in question says nothing about why the
pressure is changing,
|
| The phrase in question says nothing about pressure at all.
The word
| pressure is not even used.
|
| > only that it does.
|
| The only thing the phrase say that anything "does", is
that the altimeter
| reads too high in certain circumstances.
|
| > The
| > effect of this pressure change on altimeter readings
can - and has
| > been - adequately explained without discussion of
temperature.
|
| The effect of this temperature change on altimeter
readings can - and has
| been -adequately explained without discussion of
temperature.
|
| > We can always discuss temperature effects once the
pressure effects
| > are understood. Trying to get someone to grasp two
separate concepts at
| > the same time when it's not necessary does only serve to
confuse the
| > student.
|
| As long as the exact same phrase gets used for two
different concepts, you
| are stuck teaching two different concepts at the same
time.
|
| Now, maybe that really means people ought to stop using
the mnemonic. But
| you and I have no control over it. Pretending that
temperature is
| irrelevant is dumb, and is likely to get someone killed.
|
| Pete
|
|

[jim rosinski]

Peter Duniho wrote:

> The phrase in question says nothing about pressure at all. The word
> pressure is not even used.

My apologies to the group for so immediately violating my own stated
rule to ignore this person's posts forever more. But I just can't sit
back and let him spew utter nonsense without challenge. Good GOD man,
when you see the phrase "high to low, look out below" in an aviation
book they mean high to low PRESSURE. They assume the reader has the
intellectual wherewithall to take it from context when they see the big
high and low pressure icons on the same page!

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.

Jim Rosinski

[Matt Whiting]

jim rosinski wrote:

> Peter Duniho wrote:
>
>> The phrase in question says nothing about pressure at all. The word
>> pressure is not even used.
>
>
> My apologies to the group for so immediately violating my own stated
> rule to ignore this person's posts forever more. But I just can't sit
> back and let him spew utter nonsense without challenge. Good GOD man,
> when you see the phrase "high to low, look out below" in an aviation
> book they mean high to low PRESSURE. They assume the reader has the
> intellectual wherewithall to take it from context when they see the big
> high and low pressure icons on the same page!

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

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

Matt

[Jim Macklin]

It is clear that they meant both pressure and temperature.


"jim rosinski" > wrote in message
news:uRwdf.2687$Mr4.335@trnddc08...
| Peter Duniho wrote:
|
| > The phrase in question says nothing about pressure at
all. The word
| > pressure is not even used.
|
| My apologies to the group for so immediately violating my
own stated
| rule to ignore this person's posts forever more. But I
just can't sit
| back and let him spew utter nonsense without challenge.
Good GOD man,
| when you see the phrase "high to low, look out below" in
an aviation
| book they mean high to low PRESSURE. They assume the
reader has the
| intellectual wherewithall to take it from context when
they see the big
| high and low pressure icons on the same page!
|
| 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.
|
| Jim Rosinski

[Peter Duniho]

"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

[jim rosinski]

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

[Peter Duniho]

"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?

[Kev]

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

[Happy Dog]

"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

[Jim Macklin]

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
|
|

[Matt Whiting]

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

[Peter Duniho]

"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

[Jim Macklin]

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
|
|