Altimeter Question

On 2008-04-17, WingFlaps wrote:
Urban legend? O, it was not Newquay but Newlyn (both in cornwall). The
datum is sea level as set the British Admiralty back then so the
obvious Q code would have been QNH. Look up the history of the naval
tidal observatory if you don't believe it.

Source, please. The Q codes are just as Stefan said: randomly assigned.
They were chosen that way so as not to conflict with any nation's callsign
blocks (to this day, there are no callsigns assigned with Q as the first
letter). The apparent relationship between QNH and Newlyn Harbor is purely
coincidental.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
Fairmont, MN (FRM) (Yes, that's me!)
AMD Zodiac CH601XLi N55ZC (ordered 17 March, delivery 2 June)

On 2008-04-17, 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 or altimeter setting. For example, "Fairmont altimeter two niner
niner eight".

In radio procedure, using Q codes in speech is technically improper,
although it's done all the time (at least on the ham bands). The FAA, being
sticklers for proper procedure, would naturally include this bit. There are
no Q codes in use in aviation in the US any more, TTBOMK.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
Fairmont, MN (FRM) (Yes, that's me!)
AMD Zodiac CH601XLi N55ZC (ordered 17 March, delivery 2 June)

On Thu, 17 Apr 2008 06:51:24 -0700 (PDT), terry
wrote:

On Apr 17, 11:38*pm, Stealth Pilot
wrote:
On Thu, 17 Apr 2008 07:30:56 -0400, "Barry" wrote:
I am confused by this practice commercial nav question. ( at least I
am confused by the answer in the book which was b. but I think both a
and c are correct), but I appreciate some other opinions.

Day 1 Altimeter reads elevation of 1390 feet with 1013 HPa set on
subscale
* * * * ( thats equivalent to 29.92 inches of Hg for the US folks)
Day 2 Altimeter reads elevation of 1000 feet
Assuming the altimeter subscale was not changed between day 1 and day
2 it could be said that

a. The QNH is higher on day 2
b. The QNH is lower on day 2
c. The pressure altitude at the airport is lower on day 2
d. *The atmospheric pressure at the aerodrome has not changed.

I agree with you - answers a and c are both correct. *Day 2 QNH is about 1026.

playing with an altimeter here in my lap.
simulating 1390 by setting 390. the qnh reads as 1032.

moving the needle lower sees the qnh values going lower.

so to correct for the reduced reading I would need to move the qnh the
other way.(increase it)
I agree a is correct from playing with an actual altimeter.
c is correct just from reading the data in the question.

fwiw
Stealth pilot- Hide quoted text -

gday Stealth,
I just think of an altimeter as being a inverse pressure guage cos
pressure decreases with altitude, so for altitude reading to have gone
down , atmospheric pressure has to have gone up.
I gotta ask, why have you got an altimeter in your lap?
Terry

that's like the goon show joke. turn the knob on your side.
but I dont have a knob on my side. ...there's one on the door though.

anyway it is the old altimeter out of my auster restoration. it lives
with a few other instruments in the cupboard behind me as I type.

Hi,

In article ,
Bertie the wrote:
But, like sticking to imperial measurements, I think you stand alone.

What, like altitude in feet, altimiter settings in inches of mercury,
distance in miles, volume in gallons? Mr. Kettle, allow me to introduce
you to Mr. Pot

Britain is still clinging to a number of archaic aviation terms (you
still gotta know which direction to go whatever you choose to call it!)
One of my favorites is the "Pan" call. Nobody uses that anymore except
you guys. I had an entertaining few minutes in Germany listening to some
Nigel making one of these a few years back. It went something like this.
The Nigel Skipper is played Terry Thomas and the German controller by
Hardy Kruger in this re-creation.

Boffo Air 2234 "Rhine, Boffo 2234, PAN PAN PAN"
ATC "Station calling?"
BA 2234 "Rhine this is Boffo 2234, PAN PAN PAN"
ATC. "Boffo 2234, pass your message"
BA 2234 "Rhine, this is Boffo 2234, PAN PAN PAN"
ATC, "Boffo 2234, say again?"
BA2234 "Rhine, this is a PAN call from Boffo 2234"
(at this point you can almost hear the Boffo skiper thinking "bloody
foreigners"
ATC, "Boffo 2234, are you declaring an emergency?"
BA2234 "Negative Rhine, Boffo 2234 is making a PAN call"
ATC, -silence-
BA 2234, Rhine, we have a pasenger having a heart attack, we're mkaing a
PAN call"
ATC, "Boffo 2234, do you wish to declare an emergency?"
BA 2234 "Nega- Oh, yes, yes, we're declaring an emergency, we'd like to
divert to Frankfurt immediatly. "
ATC, roger 2234, fly heading 330 and descend now to FL 150"

No ****, this really happened. I think it actually took longer than
this. The Brit captain just wouldn't let go....

The PAN actually sounds to me like a good idea, but as I always say I'm
still a lowly stude! Being able to differentiate between a Mayday (basically
aircraft in imminent danger) and PAN (something that needs priority but
nothing that will endanger the aircraft in short order) seems like a good
idea to me.

Anyway, the formt of his PAN PAN call was all wrong according to CAP 413

That's my current bug-bear actually. The only exam I've got left to do
(apart from the Skills test) is the R/T practical. On this, unless you're
word perfect on the Mayday call you've failed, but what are the odds of a
controller ignoring your mayday because you forgot (for example) your pilot
qualifications in the mayday call?

Andy

On Thu, 17 Apr 2008 12:57:57 GMT, Larry Dighera
wrote:

On Thu, 17 Apr 2008 02:20:46 -0700 (PDT), terry
wrote in
:

I am confused by this practice commercial nav question. ( at least I
am confused by the answer in the book which was b. but I think both a
and c are correct), but I appreciate some other opinions.

Day 1 Altimeter reads elevation of 1390 feet with 1013 HPa set on
subscale

http://en.wikipedia.org/wiki/Mbar
Atmospheric air pressure is often given in millibars where
"standard" sea level pressure is defined as 1013.25 mbar (hPa),
equal to 1.01325 bar. Despite millibars not being an SI unit, they
are still used locally in meteorology in some countries to
describe atmospheric pressure. The SI unit is the pascal (Pa),
with 1 mbar = 100 Pa = 1 hPa = 0.1 kPa. Meteorologists worldwide
have long measured air pressure in millibars. After the
introduction of SI units, others use hectopascals (which are
equivalent to millibars) so they could stick to the same numeric
scale. Similar pressures are given in kilopascals in practically
all other fields, where the hecto prefix is hardly ever used. In
particular, Canadian weather reports use kilopascals (which could
also be called centibars).


Torricelli started it all off. if you are the first guy in the world
with a barometer what do you call the measure of the atmospheric
pressure measured on that barometer. a bar(ometer). divide the value
into a thousand to give you some nice fine numbers to measure with and
you have the millibar.

pascal is just a johhny come lately in pressure measurements.

the poms worked out that 14.8lbs per square inch = 1 bar(ometer)

Stealth ( I'm with torricelli) Pilot

On Thu, 17 Apr 2008 14:54:53 +0000 (UTC), Bertie the Bunyip
wrote:

terry wrote in news:179c2f21-99ad-4415-a9b2-
:

On Apr 18, 12:07*am, Bertie the Bunyip wrote:
terry wrote in news:234756e2-a583-4cbc-8f42-
:

I am confused by this practice commercial nav question. ( at least
I
am confused by the answer in the book which was b. but I think both
a
and c are correct), but I appreciate some other opinions.

Day 1 Altimeter reads elevation of 1390 feet with 1013 HPa set on
subscale
* * * * *( thats equivalent to 29.92 inches of Hg for the US f
olks)
Day 2 Altimeter reads elevation of 1000 feet
Assuming the altimeter subscale was not changed between day 1 and
day
2 it could be said that

a. The QNH is higher on day 2
b. The QNH is lower on day 2
c. The pressure altitude at the airport is lower on day 2
d. *The atmospheric pressure at the aerodrome has not changed.

It's A. It could also be C if the airfield has a serious subsidance
problem.

you are really confusing me now Bertie, I got learned that the
pressure ht was wot your altimeter reads when you have 1013.2 in the
window ( or 29.92 for you ...or maybe not cos everyone knows bunyips
are aussies ) 1000 is lower than 1390 therefore pressure altitude is
lower on day 2.. surely!.


Yer right, of course, I just couldn't resist the joke! There's a name
for that, if I'm not mistaken, and it's QNE. But theyre going for A, I'm
pretty sure and made an error in what thye were trying to say in C. I'm
bi-barometric, BTW.

Bertie

bi-barometric? is that as bad as being queer :-)

In rec.aviation.student Andy Hawkins wrote:
The PAN actually sounds to me like a good idea, but as I always say I'm
still a lowly stude! Being able to differentiate between a Mayday (basically
aircraft in imminent danger) and PAN (something that needs priority but
nothing that will endanger the aircraft in short order) seems like a good
idea to me.

Given the rarity of emergency calls, it seems like the important thing is
to make the emergency known in a simple and easy fashion first, then work
out the details later on as they're needed. The distinction is useful, but
I think that it's not worth putting extra workload on the pilot to figure
out just what degree his emergency is in his moment of crisis.

--
Michael Ash
Rogue Amoeba Software

Stealth Pilot wrote:


bi-barometric? is that as bad as being queer :-)

Only half the time.

On 04/18/08 08:38, Michael Ash wrote:
In rec.aviation.student Andy Hawkins wrote:
The PAN actually sounds to me like a good idea, but as I always say I'm
still a lowly stude! Being able to differentiate between a Mayday (basically
aircraft in imminent danger) and PAN (something that needs priority but
nothing that will endanger the aircraft in short order) seems like a good
idea to me.

Given the rarity of emergency calls, it seems like the important thing is
to make the emergency known in a simple and easy fashion first, then work
out the details later on as they're needed. The distinction is useful, but
I think that it's not worth putting extra workload on the pilot to figure
out just what degree his emergency is in his moment of crisis.


If the pilot is in a moment of crisis, then an emergency should be declared.
PAN is used when it is not at that level.


--
Mark Hansen, PP-ASEL, Instrument Airplane, USUA Ultralight Pilot
Cal Aggie Flying Farmers
Sacramento, CA

Andy Hawkins wrote in
:

Hi,

In article ,
Bertie the wrote:
But, like sticking to imperial measurements, I think you stand alone.

What, like altitude in feet, altimiter settings in inches of mercury,
distance in miles, volume in gallons? Mr. Kettle, allow me to
introduce you to Mr. Pot


I'm more of a frying pan than a kettle.

And you'll notice i have not excluded americans in this thread.

Britain is still clinging to a number of archaic aviation terms (you
still gotta know which direction to go whatever you choose to call
it!) One of my favorites is the "Pan" call. Nobody uses that anymore
except you guys. I had an entertaining few minutes in Germany
listening to some Nigel making one of these a few years back. It went
something like this. The Nigel Skipper is played Terry Thomas and the
German controller by Hardy Kruger in this re-creation.

Boffo Air 2234 "Rhine, Boffo 2234, PAN PAN PAN"
ATC "Station calling?"
BA 2234 "Rhine this is Boffo 2234, PAN PAN PAN"
ATC. "Boffo 2234, pass your message"
BA 2234 "Rhine, this is Boffo 2234, PAN PAN PAN"
ATC, "Boffo 2234, say again?"
BA2234 "Rhine, this is a PAN call from Boffo 2234"
(at this point you can almost hear the Boffo skiper thinking "bloody
foreigners"
ATC, "Boffo 2234, are you declaring an emergency?"
BA2234 "Negative Rhine, Boffo 2234 is making a PAN call"
ATC, -silence-
BA 2234, Rhine, we have a pasenger having a heart attack, we're
mkaing a PAN call"
ATC, "Boffo 2234, do you wish to declare an emergency?"
BA 2234 "Nega- Oh, yes, yes, we're declaring an emergency, we'd like
to divert to Frankfurt immediatly. "
ATC, roger 2234, fly heading 330 and descend now to FL 150"

No ****, this really happened. I think it actually took longer than
this. The Brit captain just wouldn't let go....

The PAN actually sounds to me like a good idea, but as I always say
I'm still a lowly stude! Being able to differentiate between a Mayday
(basically aircraft in imminent danger) and PAN (something that needs
priority but nothing that will endanger the aircraft in short order)
seems like a good idea to me.

Anyway, the formt of his PAN PAN call was all wrong according to CAP
413


I can't remember precisely what he said, but the jist of the
conversation is there and it's pretty much the way it happened. I don;'t
even know the format off th etop of my head, but he probabyl did it
right.

That's my current bug-bear actually. The only exam I've got left to do
(apart from the Skills test) is the R/T practical. On this, unless
you're word perfect on the Mayday call you've failed, but what are the
odds of a controller ignoring your mayday because you forgot (for
example) your pilot qualifications in the mayday call?

Pretty slim. I've never even used the Mayday and I've had several
emerencies and just declared an emergency and got everything I needed. I
think I'd ony use a Mayday to cut through heavy radio traffic if it was
neccesary.


Bertie