Altimeter settings: QNH versus QFE
kirk....@gmail.com
"flat" state from a "mountainous" state and noticed that every glider
pilot I have met and flown with in the "flat" state sets his altimeter
to zero (a QFE setting) instead of field elevation. Back in my old
stomping grounds, all my glider friends set field elevation (QNH).
I find this a bit disturbing - even dangerous. It's tough to
deconflict altitude on the radio when you don't know what the other
glider has set his altimeter to!
In response to my questions about why this practice of setting the
altimeter to zero is so common, invariably the response is "that's the
way I was taught" (from both old and new pilots) or that "it's easier
for the student to learn that way" from instructors. Does this mean
that flatland student pilots are mathematically challenged, while those
in mountainous areas are not?
I also hear "it's easier to tell how high up I am when landing". Huh?
What happened to no-altimeter/TLAR patterns? Or are people being
taught rigid altitudes in the pattern?
So - what gives? Is this technique commonly taught? Do instructors
really believe it helps their student? Is it even legal (how do you
get a current altimeter setting during a long flight)?
No prize for figuring out my opinion about this practice...
And please, no tangential discussion about using QFE for IMC approaches
- unless you have two altimeters in your glider...
Kirk
66
Bill Daniels
field elevation are generally those who have no cross country experience in
either gliders or airplanes and can't grasp the concept of landing at
another location with a different elevation.
I teach setting the altimeter to QNH and how to get an updated altimeter
setting by radio. Complete knowledge of altimetry is required of all pilots
regardless of the aircraft they fly. I also teach TLAR for off-field
landings where the field elevation may be unknown.
BTW, does your altimeter read field elevation before takeoff when set to
local pressure? Most glider altimeters don't and should be calibrated.
bildan
<kirk....@gmail.com> wrote in message
news:1117553889.1...@g49g2000cwa.googlegroups.com...
Vaughn Simon
> So - what gives? Is this technique commonly taught? Do instructors
> really believe it helps their student? Is it even legal (how do you
> get a current altimeter setting during a long flight)?
I could make an impassioned case for either setting, but 91.121(a)(1)
settles the issue. The altimiter is always set at the current reported
altimeter setting of an appropriate available station or at the elevation of
the departure airport. That is what I have always taught my students.
Of course, here in south Florida the question is pretty academic.
Vaughn
Papa3
T o d d P a t t i s t wrote:
> "Vaughn Simon" <vaughnsimo...@att.net> wrote:
>
> > I could make an impassioned case for either setting, but 91.121(a)(1)
> >settles the issue.
>
> No it doesn't. 91.121 only requires that the altimeter be
> set to the "reported altimeter setting of a station" when
> the pilot is attempting to "maintain the cruising altitude
> or flight level of that aircraft, as the case may be" A
> glider can't maintain a cruising altitude and is not
> required to do so, so he need not set the altimeter as
> required under 91.121.
Todd,
This may be your "strict" interpretation, but I wonder how the
Federales would react if an incident came up in which the altimeter
setting was a factor. Suppose just for kicks that you barely busted
(say 300 feet) the floor of the Class C airspace at Allentown during a
ridge run and had the misfortune to be doing that just as USAIR Flight
472 was on initial approach to ABE. It was a close call, and the FO
was in a grumpy mood anyway after his 33% pay cut, so he decided to
press the issue and reported the near miss to Approach. Now, for
whatever reason, you happened to land out at Reading, just as the local
DE is finishing up a check flight. He was talking to the home office
before heading out, and somebody mentioned the near miss with a glider
with a big WH painted on the tail.
He gets to chatting with you, and he notices that the altimeter is way
off from the current reported setting at RDG. Starts you down an
interesting line of discussion, no? Given the way things are going,
you can envision 91.13 being invoked.
Anyway, obviously this is stretching it a bit, but the point to me is
that the POTENTIAL downsides of using QFE rather than QNH (which is the
"reported altitude" on all AWOS/ASOS/Weather Observer reports according
to the FAA's own Surface Weather Observing manual) outweigh any
potential pros. I've always taught QNH to students, and I rarely have
anyone who can't do the math after a few flights. If somebody can't
subtract, say, 400 feet from an altimeter showing 1500 feet to figure
out that we're "about" 1100 feet over the home airport, then I wonder
how they're going to handle things like "an approximately 25:1 glide
angle to get home" or to "add half the estimated headwind to the
nominal Best L/D speed".
Just my 0.02,
P3
Vaughn
"T o d d P a t t i s t" <tpat...@dontspamme.snet.net> wrote in message
news:2n8p91p2b9un09os6...@4ax.com...
>> I could make an impassioned case for either setting, but 91.121(a)(1)
>>settles the issue.
>
> set to the "reported altimeter setting of a station" when
> the pilot is attempting to "maintain the cruising altitude
> or flight level of that aircraft, as the case may be" A
> glider can't maintain a cruising altitude and is not
> required to do so, so he need not set the altimeter as
> required under 91.121.
OK, I understand what you are saying, but the sentence starts out with
"Each person operating an aircraft shall..." and by that I assume that they
mean everybody. Further, while you don't maintain a CERTAIN altitude in a
glider, you are supposed to maintain a SAFE altitude and you determine that with
your altimeter.
In short, while your interpretation may fly with the FAA, I would hate to
have my license depending on it.
>
> You didn't list the impassioned arguments you could have
> made, but they boil down to
>
> FIELD ZERO
> 1) you can't hold altitudes in cruise or patterns,
> 2) you're highly likely to land in a field, where you don't
> know field elevation anyway
> 3) it *is* easier for the student landing at his own
> airport.
> 4) Even if you teach using FIELD ELEVATION/91.121, the
> student won't really learn to do the mathematical
> manipulation. Students will just learn to turn base at 500'
> plus field elevation instead of 500' Glider training does
> not usually involve landing at other airports.
>
> FIELD ELEVATION/91.121
> 1) you may land at another airport
> 2) in flight changes easier
> 3) CDAS etc airspace is charted MSL
> 4) your local FAA official gets antsy seeing field zero in a
> glider
> 5) it is really difficult to change over if you learn under
> FIELD ZERO
> 6) when you mix with other gliders from other fields radio
> reports of altitude are not much help to you or them
> 7) most contest pilots do not use FIELD ZERO.
You did a better job there than I would have. Individually, they support
two very convincing, yet opposing, viewpoints.
Vaughn
Kilo Charlie
> "flat" state from a "mountainous" state and noticed that every glider
> pilot I have met and flown with in the "flat" state sets his altimeter
> to zero (a QFE setting) instead of field elevation. Back in my old
> stomping grounds, all my glider friends set field elevation (QNH).
Wow....I'm not a CFIG but am one of Kirk's "glider friends in his old
stomping grounds" and for the life of me cannot even believe this discussion
is happening!!!
To do this is an enormous crutch and dangerous for anyone that will ever fly
outside of their local airport environment. How about mountains? How about
large towers there in the "flatlands" where elevations can vary even there
by a few hundred feet making your chart worthless. And as 66 points out,
how about the old "hey I'm in the same area you just said you were in,
what's your altitude?". How about the powered plane that is transitioning
your area and is smart enough to read the chart, see that there is a glider
ops there and makes a radio call to say that he is overflying from the south
at X altitude?
Finally the last but maybe best reason to NOT do this is that when stressed
we all regress to what we were first taught and our natural instincts. If
one of these folks taught on the QFE basis starts taking powered lessons
(God forbid!) or heads to another mountainous glider site and gets in
trouble they are going to revert to thinking in QFE format and that may end
up being a fatal error.
Casey Lenox
KC
Phoenix
(who just got back from Moriarty where it was supposed to be good but
watched it OD for 3 days!)
BTIZ
it does not adjust that far
2) how do you stay out of the overlying Class B airspace and ModeC veil
restrictions if you cannot accurately measure altitude above sea level
3) how do you stay out of Class A airspace on a wave or thermal flight (see
#2)
4) how do you know how high you need to be to clear that ridge line ahead or
that you have final glider altitude for that airport that is not home
5) you have some idea of the airport or "ground" elevation you are going to
land on based on reading the contour lines on the chart or airport
information
our field elevation is 2833 and we just spent a weekend at Lone Pine CA,
elev 3680
or maybe Cal City, 2454, or Tehachipe, 4220, and lets not even get started
on the great soaring sites in Utah or Arizona or Colorado.
Best to learn the mental math now.. then later when you travel west for the
first time.
BT
<kirk....@gmail.com> wrote in message
news:1117553889.1...@g49g2000cwa.googlegroups.com...
BTIZ
>
> Yes.
No
>
>>>(how do you get a current altimeter setting during a long flight)?
>
> You don't.
you do.. you listen to the local ATIS or ASOS or AWOS or check with FSS or
ATC on freq and find out what they are using in the local area
BT
Stefan
> you do.. you listen to the local ATIS or ASOS or AWOS or check with FSS or
> ATC on freq and find out what they are using in the local area
I've yet to see a glider with an accurately calibrated altimeter.
Stefan
Stefan
> How about mountains? How about
> large towers there in the "flatlands" where elevations can vary even there
How about looking out of the window?
Stefan
Stefan
obvious reasons. But then, aerobatic flights are usually strictly local.
Stefan
Bert Willing
could be compared to Northern Florida) I always used a QFE setting with the
field 600ft MSL. Airspace regulations weren't that touchy in these days, and
sailplane altimeters aren't that precise anyways so there is just no point
to have it set at 400ft or 600ft. If you rely on judging your altitude by an
altimeter during the pattern for an outlanding, you shouldn't go x-country
in the first place. If you run into a high antenna or a tower on a hillside,
you should think about getting a new prescription for your glasses.
The last 15 years in the mountains are another story though.
--
Bert Willing
ASW20 "TW"
"Stefan" <stefan@mus._INVALID_.ch> a écrit dans le message de news:
d7jmnn$7ms$2...@news.hispeed.ch...
Paul
> I've yet to see a glider with an accurately calibrated altimeter.
Strange.
As they are supposed to be certified instruments, they are required to be
checked every two years here in New Zealand. Along with the Transponder and
encoder.
Paul
cb...@webmail.co.za
by multiplying the meters by three and adding 4 500ft to get the real
altitude when speaking to the ATC. I then bought a glider without a
meter altimeter - only a ft one which is set to show altitude above sea
level. No more problem when speaking to ATC but found I was doing
reverse calculations to find out how high I was above the hard stuff.
Then I set my palm up with Soaringpilot which now has a digital terrain
model built in. Now I know exactly how high I am above the ground -
even when I fly cross-country in the mountain regions not far from my
airfield. My LX 5000 computer is set up to show my height above my home
field, which is more important for final glide than anything else.
Clinton Birch
LAK 12
Robin Birch
i s t <tpat...@dontspamme.snet.net> writes
>"BTIZ" <btizn...@cox.nospm.net> wrote:
>
>>Best to learn the mental math now.. then later when you travel west for the
>>first time.
>
It has been really interesting to watch this one. I fly in the UK and
this is what I have been taught to do:
If local then QFE;
if XC then QNH;
If wave flying then QNE once you go above 3,500 QNH (this is transition
round where I am I know it is different in other places). This also
applies XC if you are going near a lot of airspace;
I am taught to land without reference to the altimeter and I don't think
I have ever used it when I carry out field landings.
Not that many glider pilots in the UK have radio licences and a fair
number of gliders do not have radios so the QNH is not generally updated
beyond the departure calculation and setting.
Now, I must say that this is a reworking of what I was taught for power,
not gliding and I can't remember it ever being laid down specifically
what I should do away from local flight other than making sure that I
could land and so on without use of the altimeter.
Cheers
Robin
--
Robin Birch
Andy
T o d d P a t t i s t wrote:
It's my understanding that this procedure is also used in
airplanes in the U.K. In the U.S., airplanes will only use
QNH or QNE (above 18,000') and never use QFE.
There is always an exception to any rule. American Airlines used to
always use QFE set altimeter for approach and landing in US. I was
involved in the development of the MD-11. We developed an altimeter
setting system that allowed easy transition between QFE, QNH and STD
for the glass cockpit altimeters. American was the only US operator
that used that customer option. They would land at Denver with
altimeter reading zero after getting QFE setting from local ground ops.
(I was involved in development and flight test, not American's ops, so
any America Airlines pilots on this forum may correct this).
Andy
BTIZ
BT
"Stefan" <stefan@mus._INVALID_.ch> wrote in message
news:d7jmkn$7ms$1...@news.hispeed.ch...
Eric Greenwell
When I had my biennial check on my transponder, there was no check of
the altimeter. They did adjust the encoder to read the current pressure
altitude. I know there are strict requirements for encoder and altimeter
accuracy for IFR flight, which requires testing the encoder and
altimeter up to the altitude they will be used in. Is there some
regulation requiring an aircraft with a transponder used in VFR flight
to also have an altimeter calibration? I don't think Mode C is required,
so perhaps the regulation, if there is one, applies only if an encoder
is installed?
--
Change "netto" to "net" to email me directly
Eric Greenwell
Washington State
USA
Kilo Charlie
regulation for all aircraft in the US to have accurate altimeters?
I would like to think that mine is accurate within a certain limit since as
this discussion points out it is important. No doubt that in the conditions
that we fly in (changing pressure as the day progresses) there is some
inaccuracy but in my experience not more than a hundred feet or so and as
others have pointed out by tuning in to a local ATIS can be corrected.
Those influences are the same for whatever setting you decide to initially
use anyway.
Casey Lenox
KC
Phoenix
BTIZ
91.413 specify a 24 month check even if used for VFR only for the
transponder to report accurate altitude
AIM 7-2-3, check altimeter against know field elevation and baro setting, if
difference is greater than +/- 75ft from the known elevation. The altimeter
accuracy is suspect and should be reported to a repair station for
evaluation and correction.
The altimeter and transponder must be checked every 24 months for operations
in IFR. (91.411)
That is the only VFR "check" of the altimeter that I have found tonight. But
if the altitude or altitude reporting function (blind encoder) reports
altitude to the transponder, it must be checked every 24 months. If you
don't have a transponder, and you never fly IFR, if the baro setting
displays within 75ft of field elevation. It's "good to go".
BT
"Eric Greenwell" <flyg...@charter.netto> wrote in message
news:CHtne.1338$K66...@fe02.lga...
stephanevdv
Just another point in this discussion: when I look at an approach map of
an airfield, the pattern altitude is expressed as a height above
ground. To me, this means the easiest way of complying is to fly QFE
when entering the pattern (no mathematics needed) - providing of course
you can get the necessary information.
If you want to fly QNH, pattern altitudes should be expressed AMSL.
By the way, here in Europe (except UK, of course) glider altimeters are
in meters, not feet, thereby conforming to ICAO annex 5 whose purpose
it is to standardize units of measurement to the ISU. As the approach
maps (and other aviation maps) usually are in feet, we already have to
make computations anyhow.
It's high time we got rid of feet, knots and nautical miles! Their only
real purpose in aviation seems to be to make it more difficult to get a
pilot's licence, as you have to adjust to a new set of units. (Yes, I
know there are certain countries where they like to use outdated unit
systems. I also know the classical arguments like "a nautical mile
equals a minute of latitude", but how often do you fly true north or
south?)
--
stephanevdv
------------------------------------------------------------------------
Posted via OziPilots Online [ http://www.OziPilotsOnline.com.au ]
- A website for Australian Pilots regardless of when, why, or what they fly -
309
the history of QNH, QFE, and QNE (etc.), specifically, WHAT does the
"Q" stand for??? The "F"? The "N", the "H" or the "E"???
I can see reasons for using each and every setting, and I can see
reasons for NOT using each and every setting.
My opinion is that we should all learn to do the math (in both
directions), and I am not practicing what I've just preached (at least
when it comes to using QFE!).
Just wait until there's another mid-air, and suddenly all gliders are
required to be equipped with transponders, TCAS, ADS-B, radio
altimeters and "bitchin' betty's" to annoy pilots getting too close to
stall (or spin)...
Again, where did the "Q" come from???
-Pete
#309
kirk....@gmail.com
original post). IFR approach plates (at least in the US, where QFE
isn't used) give all approach altitudes in QHN, hence the need for an
accurate and recent altimeter setting. VFR pattern altitudes are often
given AGL, but they are pretty consistent: 1000', 1500' for jets,
perhaps 800' for gliders, etc. It really doesn't require a calculator
in the cockpit to figure out what number to put behind the needle on
the altimeter to be at the right altitude in the pattern. And it is a
lot easier to figure out the proper pattern altitude than to go through
the hassle of getting the QFE setting - assuming the airfield you are
landing at is low enough. It's a moot point in the US - ask tower for
a QFE setting and all you will get is "huh, say again?".
I understand in Europe it is common to have two altimeters in power
planes so that one can be set to QFE. Makes sense for instrument/low
vis approaches (pre-radar altimeter), if the "system" is setup for it
(QFE available from tower, appropriate approach plates, proper training
etc). Is this a correct assumption?
As far as going metric in aviation, sorry but I absolutely disagree -
metric units just don't work as well in aviation as feet/knots/NM,
IMHO. Metric altimeters are an abomination! And since almost all the
big boys (general aviation, airlines and military) use feet/knots/NMs,
everybody should. There is nothing sacred about the meter, after all -
any arbitrary unit will do if it is used consistently and satisfies the
needs of the users. Not that I expect any agreement on this point from
my European friends!
And the nice thing about nautical miles is that it is extremely easy to
get a quick distance measurement off a sectional chart by using the
nearest latitude scale - regardless of heading. Especially when the
kilometer scale is buried under the folds of the chart (or is on the
piece that got torn off to make the chart small enought to use in an
LS6's cockpit!)
My pet peeve in the US is that we usually fly in feet/knots, but set
tasks and give XC speeds in statute miles/MPH, then use kilometers for
badge and OLC flights. Absurd!
Seriously, it's interesting that the responses to the original topic of
this thread have not included any real defenders of using QFE in
gliders, just some reasons (excuses?) why it is done. Cmon, let's hear
it from you guys who are teaching it to your students!
Cheers,
Kirk
66
Stefan
> All of the aruguing aside, can anybody out there tell me a little of
> the history of QNH, QFE, and QNE (etc.), specifically, WHAT does the
> "Q" stand for??? The "F"? The "N", the "H" or the "E"???
Nothing. It's just a code, the Q-code, to be precise :-) Maybe the Q has
a story, I don't know, but the latter two letters definitely do not.
Think of it as a numbered set of commonly used phrases.
A complete list of all Q-codes is at http://www.htc.ch/de/der_Q_code.htm
(German only).
Stefan
Andy
One of the wonderful ones that stuck in my memory all these years was
"Shall I point my searchlight at a cloud, occulting if necessary, in
order to pinpoint my position" All that in 3 letters! They were used
for morse code communications before RT was available.
Andy
Bruce Hoult
"309" <pdo...@pacbell.net> wrote:
> All of the aruguing aside, can anybody out there tell me a little of
> the history of QNH, QFE, and QNE (etc.), specifically, WHAT does the
> "Q" stand for??? The "F"? The "N", the "H" or the "E"???
"Query". These are Morse radio operator's abbreviations for common
questions they might ask of or be asked by a ground station.
http://en.wikipedia.org/wiki/Q_code
QNH is I believe "Nautical Height" and QFE is "Field Elevation" though
these are more mnemonics than definitions. What is the difference
between height and elevation? If you know, please explain why QNE might
be "Nautical Elevation".. (some sources suggest the mnemonic "anywhere"
for NE)
--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------
Graeme Cant
> Just another point in this discussion: when I look at an approach map of
> an airfield, the pattern altitude is expressed as a height above
> ground.
when they used QFE. Never seen a Jepp chart in QFE - but I guess
they're produced that way for some operators.
> If you want to fly QNH, pattern altitudes should be expressed AMSL.
They almost always are on the charts I've seen.
> By the way, here in Europe (except UK, of course) glider altimeters are
> in meters, not feet, thereby conforming to ICAO annex 5
True. But in non-conformity to the great bulk of aviation globally. A
classic example of the problems of one-nation one-vote in these matters.
BTW - Aren't your altimeters in metres, not meters?
> whose purpose
> it is to standardize units of measurement to the ISU
No. Its purpose is just to standardise measurements. Feet are
perfectly good units to standardise on.
> . As the approach
> maps (and other aviation maps) usually are in feet, we already have to
> make computations anyhow.
Well stop resisting. Learn to think in feet instead of metres.
> It's high time we got rid of feet, knots and nautical miles! Their only
> real purpose in aviation seems to be to make it more difficult to get a
> pilot's licence, as you have to adjust to a new set of units. (Yes, I
> know there are certain countries where they like to use outdated unit
> systems. I also know the classical arguments like "a nautical mile
> equals a minute of latitude", but how often do you fly true north or
> south?)
ICAO working document(23/9/04): "...a study...completed in 1997,
indicated that 97% of jet aircraft worldwide were non-SI equipped
aircraft. Moreover, a growing number of non-SI equipped aircraft were
being operated by airlines of the small number of States which use SI
units."
You'll be flying in feet, knots and nautical miles for quite a while.
Better relax and go with the flow. :)
GC
Graeme Cant
> All of the aruguing aside, can anybody out there tell me a little of
> the history of QNH, QFE, and QNE (etc.), specifically, WHAT does the
> "Q" stand for??? The "F"? The "N", the "H" or the "E"???
The three letter "Q" codes date back to W/T, radio operators and Morse
code. They were a shorthand way of requesting/passing information and I
don't recall any where the other letters have any significance.
The only others I remember still in use are QDM - ILS inbound track or
runway direction and QSL - followed by a number to indicate radio signal
strength or readability.
Others (especially radio hams) may remember a lot more.
GC
kirk....@gmail.com
I was referring to the part of my original post where I said: "And
please, no tangential discussion about using QFE for IMC approaches
- unless you have two altimeters in your glider..." since I had a
feeling it would crop up and divert attention from the issue at hand.
As far as the pseudo QFE - amazing what some people will do to avoid
doing a little thinking in the cockpit.
Great discussion by all involved - I guess I'll just have to bite the
bullet and become a CFIG so I can impose my will on others!
Kirk
Nyal Williams
>I'd like to add that for aerobatic flight, it is common
>to use QFE, for
>obvious reasons. But then, aerobatic flights are usually
>strictly local.
>
>Stefan
>
Precisely!
And that is the attitude of hundreds of glider pilots
for the last 40 years. Strictly local. I was taught
that way of thinking in a J-3 cub back in 1953, and
then we used it in a glider club in the 60s.
It works fine if you are in an uncomplicated area and
stay local, but it is OLD THINKING! Hardly anyone
travelled to another site those days - even the Cessna
pilots stayed within 25 miles of the home airport (flat
country).
We have a few of those in our club -- guys who never
venture more than 10 miles away in flat land, but the
instructors don't allow it for students.
Jack
> I also know the classical arguments like "a nautical mile
> equals a minute of latitude", but how often do you fly true north or
> south?)
How often do you look at a map?
Jack
Nyal Williams
the letters QFE, QNH and that third one, which I have
already forgot. I'm even more surprised that no one
has asked what they mean.
QFE = field elevation
QNH = pressure level indicating altitude above sea
level
Q__ = pressure altitude for a standardized pressure
to use for high altitudes (above 18K in the US)
Now, What does the Q mean?
What are the words for NH and for that other one?
Tony Verhulst
> equals a minute of latitude", but how often do you fly true north or
> south?)
Airplane pilots like to look at the length of a course line, compare it
to the minutes latitude and know exactly the distance without the use of
any other tools. I understand that there are other tools. I was raised
as a Dutch man and brought up with the metric system - and prefer it.
But, to me nautical miles make sense, YMMV.
On another topic, why have horizontal speed in km/h and vertical speed
in meters/sec? To me, this is odd. If the units were the same, you could
simply divide one into the other and get the L/D - again, YMMV.
Tony V.
Bill Daniels
"Tony Verhulst" <n...@thankyou.com> wrote in message
news:KqOdnfvifLj...@comcast.com...
Knots, MPH, KPH, meters/sec are just numbers. Just read the POH and fly the
numbers.
However, I have a beef with metric altimeters. The large hand reads 1000
meters per rev. An imperial units altimeter reads 1000 feet per rev. 1000
meters = 3281 feet so the metric altimeter is less than 1/3 as sensitive as
the one based on feet. To me, that seems inadequate.
I like to see the altimeter hand move with small changes in altitude.
That's confirmation that all is well in the instrument panel. I've seen
haywire varios insistently reading up while the altimeter was winding down.
I'm not sure I would have spotted that as quickly with a metric altimeter.
I suppose there is no reason that a metric altimeter could not be more
sensitive. With today's digital technology, 100 meters per rev should be
possible. I've never seen one that sensitive.
Bill Daniels
Eric Greenwell
> I like to see the altimeter hand move with small changes in altitude.
> That's confirmation that all is well in the instrument panel. I've seen
> haywire varios insistently reading up while the altimeter was winding down.
> I'm not sure I would have spotted that as quickly with a metric altimeter.
>
> I suppose there is no reason that a metric altimeter could not be more
> sensitive. With today's digital technology, 100 meters per rev should be
> possible. I've never seen one that sensitive.
Actually, even yesterday's digital technology already provides very
sensitive altimeters in our varios, GPS units, or flight computers.
These are digital readouts, of course, not hands, but I find myself
looking at my Cambridge 302 altimeter reading much more than the
mechanical one. You can use it in feet or meters, and have plenty of
sensitivity.
The next mechanical altimeter I buy will likely be an INsensitive unit,
like one of the 0-10,000' or 0-20,000 single hand units for less than $150.
now...@volcanomail.com
morning and set all the altimeters to 29.92 (or the current setting)
and see how much variation there is in the altitude read outs. You may
be surprised. I certainly was when I did it.
Bruce Hoult
"Bill Daniels" <bil...@comcast.net> wrote:
> However, I have a beef with metric altimeters. The large hand reads 1000
> meters per rev. An imperial units altimeter reads 1000 feet per rev. 1000
> meters = 3281 feet so the metric altimeter is less than 1/3 as sensitive as
> the one based on feet. To me, that seems inadequate.
Some gliders I have flown have altimeters marked in feet, but 3000 ft
per revolution rather than 1000.
Presumably it's possible to design a single unit for either metric or
imperial use and tweak the calibration by the 10% difference.
pr...@prep.synonet.com
...
> QFE = field elevation
> QNH = pressure level indicating altitude above sea
> level
> Q__ = pressure altitude for a standardized pressure
> to use for high altitudes (above 18K in the US)
> Now, What does the Q mean?
They come from morse code days, and there are hundreds of them
covering all sorts of radio, marine, met, and aviation conditions.
Defined by the ITU way back.
--
Paul Repacholi 1 Crescent Rd.,
+61 (08) 9257-1001 Kalamunda.
West Australia 6076
comp.os.vms,- The Older, Grumpier Slashdot
Raw, Cooked or Well-done, it's all half baked.
EPIC, The Architecture of the future, always has been, always will be.
GeorgeB
wrote:
>309 wrote:
>
>> All of the aruguing aside, can anybody out there tell me a little of
>> the history of QNH, QFE, and QNE (etc.), specifically, WHAT does the
>> "Q" stand for??? The "F"? The "N", the "H" or the "E"???
>
>The three letter "Q" codes date back to W/T, radio operators and Morse
>code. They were a shorthand way of requesting/passing information and I
>don't recall any where the other letters have any significance.
I don't know, but wonder with the thought in creating Morse (most
common letters easiest to send), if the letters for the most common
(at the time?) were the least confusing and/or shortest sent in
combination?
stephanevdv
Funny to get exactly the reactions one could foresee. OK, I admit I
don't have much hope of getting the ISU units accepted in aviation, but
the "nautical mile/minute of latitude" story has been dealt with long
ago, shortly after the French Revolution. There still are French (I'm
Belgian, please don't mix us up) survey maps with longitude and
latitude in grades, not degrees (400 grades = 360 degrees). You then
have: 1 hundredth of a grade = 1 kilometre (UK) / kilometer (USA). Just
as efficient (or inefficient), and decimal, but it hasn’t been able to
replace the 360 degree system, not even in the ISU. Oh, by the way,
this geodetic system uses the Paris meridian as zero, not the Greenwich
one.
> me, this is odd. If the units were the same, you could simply divide
> one into the other and get the L/D
dividing indicated speed by sink anyhow: the value will vary wildly in
a relatively short time, and wind can play havoc with this kind of
calculation.
Stefan
> Just
> as efficient (or inefficient), and decimal, but it hasn’t been able to
> replace the 360 degree system,
Just to add confusion to the discussion: The decimal system has been
about the dumbest idea which has happened to mankind. The phoenicians
got it right by using the duodecimal system (actually, they used even
the 60-system), which is much more suited for most real life situations.
But some dimmer folks replaced it by the decimal system, because they
couldn't do the math without using their fingers. So I fear we have to
live with that.
Stefan
stephanevdv
And what about computer folks?
They can't go further than 0 and 1!
01-- Zero One
USA.
Larry
"Stefan" <stefan@mus._INVALID_.ch> wrote in message
news:stefan@mus._INVALID_.ch:
Paul Lynch
That may work for gliders, but not necessarily for other type aircraft. The
math is simple using the nautical system with lots of shortcuts to do the
math simply. Mach number means nothing to glider pilots (save the shuttle
dudes), but it does to us jet jocks.
"stephanevdv" <steph...@REMOVETHISOziPilotsOnline.com.au> wrote in
message news:stephanev...@OziPilotsOnline.com.au...
>
> Just another point in this discussion: when I look at an approach map of
> an airfield, the pattern altitude is expressed as a height above
> ground. To me, this means the easiest way of complying is to fly QFE
> when entering the pattern (no mathematics needed) - providing of course
> you can get the necessary information.
>
> If you want to fly QNH, pattern altitudes should be expressed AMSL.
>
> By the way, here in Europe (except UK, of course) glider altimeters are
> in meters, not feet, thereby conforming to ICAO annex 5 whose purpose
> it is to standardize units of measurement to the ISU. As the approach
> maps (and other aviation maps) usually are in feet, we already have to
> make computations anyhow.
>
> It's high time we got rid of feet, knots and nautical miles! Their only
> real purpose in aviation seems to be to make it more difficult to get a
> pilot's licence, as you have to adjust to a new set of units. (Yes, I
> know there are certain countries where they like to use outdated unit
> systems. I also know the classical arguments like "a nautical mile
> equals a minute of latitude", but how often do you fly true north or
> south?)
>
>
Tony Verhulst
Even more fun, we set QNH of 500 ft. When the student is not looking,
I'll dial in -500 ft. Most don't catch it - the first time.
Tony V.
Tony Verhulst
> 'duodecimal system' -- We use that all the time in libraries in the USA.
Groan :-).
Tony V.
Jack
the field = 0. The field was only about 600' MSL so it wasn't a real
big deal, or so I thought at the time. I have just gotten back into
soaring and I am doing my very best to break that habit, and use field
elevation, which for me is now 300 or so. It is taking a while to break
a 19-year habit, but I'm about there. The people that taught me to fly
didn't think they were doing anything wrong. They have nothing to be
ashamed of, that's for sure. I'm proud to say I know all but one of
them... the one that told me I needed to give up, and that I'd never
learn to fly... a real morale builder.
My point is that maybe instructors should be teaching students to add
the field elevation in their decision making. If they're expected to do
that, they will. If you expect them to be stupid, they will. Some have
stated that they don't have a choice because their airports are too
high. They have to teach this the right way. Their students have to
learn this and all do. If I were an instructor, I would not solo a
student that couldn't do this with proficiency. That student will then
know this as instinct, rather than having to unlearn a bad habit. This
is important in our mobile society. I've been moved twice in 8 years. I
expect to move again this coming winter. I am now comfortable using the
MSL field elevation as a start point, and my opinion is that this
should be universal for all students.
Just my nickels worth... and you thought I just had 2 cents...
Jack Womack
nimbusgb
Ian
F.L. Whiteley
> 309 wrote:
>
>> All of the aruguing aside, can anybody out there tell me a little of
>> the history of QNH, QFE, and QNE (etc.), specifically, WHAT does the
>> "Q" stand for??? The "F"? The "N", the "H" or the "E"???
>
> Nothing. It's just a code, the Q-code, to be precise :-) Maybe the Q has
> a story, I don't know, but the latter two letters definitely do not.
> Think of it as a numbered set of commonly used phrases.
>
> A complete list of all Q-codes is at http://www.htc.ch/de/der_Q_code.htm
> (German only).
>
> Stefan
Don't forget the Z codes.
http://groups.msn.com/ctoseadogs/34z34signals.msnw
Frank
csle...@hotmail.com
field zero because this is how I was taught, BUT... I fly in Florida.
Our place is only 200'.
However, the thought of eventually going cross country has me
considering dumbing this QFE setting, but a few complications entered
my mind. Not to mention the accuracy of the instuments in club and
commercial planes. Nothing that simple math can't solve of course, but
nonetheless important when trying to operate with others in the flying
environment.
Examples:
Cloud base reported by other pilots as 4000',what are they determining
that on? QFE or QNH.
Signal to tow pilot to release me at 2000'. I pop off sooner.
Towing out and looking out for the magic 200'mark to turn back to field
in a rope break.
Granted, communication with tow pilot, incorporating the math, and of
course using good old "That looks about right" may solves these
mentioned scenarios, but I just thought, would it not be nice if QNH
was universally used by everyone even if my home field is a measley
little 200'MSL.?
kirk....@gmail.com
Some suggestions per your questions (with the caveat that a discussion
with a CFIG that you trust is undoubtedly a much better source of
guidance!):
The cloud base question gets to the very heart of this issue, however
really only on a theoretical basis - cloud bases have been known to
vary quite a bit, cloud to cloud! And here it gets interesting,
because ceilings are given AGL for the field in question - because
instrument approaches have minimums based on how low the clouds are -
AGL! But cloud heights are given in MSL. Hopefully we aren't in the
situation of shooting an approach to mins in our gliders!
Tows are usually billed in altitude gained on tow - so it's really
difference between takeoff and release altitude. You got to do the
math - but since most pilots seem to like nice even tow numbers (odd,
since the good lift always seems to be at either 900 ft or something
like 1700 ft) it really isn't a demanding calculation to make. Anyway,
just release, and trust me the tow operation will figure out a way to
bill you! Seriously - at a strange field with an odd altitude, just do
the math before hooking up, and when you see that number, you are
there.\\
The "magic" 200 ft - if you still use it, instead of TLAR - is the same
thing, do the math before hooking up as part of your checklist (the E
of CBSIFTCBE, for example) and it will work anywhere.
For those who like a visual reminder, there are moveable "bugs" that
can be attached to the altimeter face that can be set at the field
elevation. Cheap and easy.
Kirk
66
Robin Birch
<greeley@_no_spam_greeleynet.com> writes
whole list there are loads of things to do with radio comms as well as
the various things to do with aerial navigation.
They are widely used in amateur radio as well as in flying.
Robin
--
Robin Birch
F.L. Whiteley
Quite right. One may send quite a complex message using a few Q & Z
signals, text, and numbers.
Frank
Dave Martin
http://www.zerobeat.net/qrp/qsignals.html
At 22:00 06 June 2005, F.L. Whiteley wrote:
>Robin Birch wrote:
>
>> In message , F.L. Whiteley
309
QNH, QFE, QNE, QUH, WTF...etc...
One of my aerospace co-workers (and a fellow Flight Test Engineer) was
musing aloud one day: "We all know what it MEANS, but what do the
letters STAND for??? Where did they come from?" As if QNH stood for
"Quintesstial Normalized Height," and QFE stood for "Quiet Field
Elevation," or ???
I tried to warn him that it was foolish to try and make sense out of
any three letters...take "FAA," for example... ;-)
Regards,
-Pete
#309