Altimeter settings: QNH versus QFE

I have a question for you CFIG's out the I recently moved to a
"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

I've found that instructors who teach setting the altimeter to read zero at
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

wrote in message
oups.com...
I have a question for you CFIG's out the I recently moved to a
"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

wrote in message
oups.com...

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

T o d d P a t t i s t wrote:
"Vaughn Simon" 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

"T o d d P a t t i s t" wrote in message
...
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.

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

wrote in message
oups.com...
I have a question for you CFIG's out the I recently moved to a
"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!)

1) we can't turn the altimeter setting enough to set it to zero elevation..
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

wrote in message
oups.com...
I have a question for you CFIG's out the I recently moved to a
"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

Is it even legal

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

BTIZ wrote:

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

Kilo Charlie wrote:

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