Altimeter setting

[Tom]

As a glider pilot, when are you allowed to use a zero altimeter
setting?

Back in July, I asked the FAA for a legal opinion regarding FAR
91.121. Yesterday, I finally received a response.

There is reason for a continued dialog, and I am continuing the
discussion with the FAA legal department.

This Saturday, immediately prior to the third Glider Safety Webinar,I
will provide subscribers to the webinar the exact wording of the FAA
response.

To join us in this discussion, please sign up for the third webinar on
our web site: www.eglider.org

Tom Knauff

[Tony]

91.121 is pretty clear that the only time an altimeter should be set
to zero is if you are taking off from sea level

[Mike Schumann]

Why not just post the FAA response here?

[jim wynhoff]

> to zero is if you are taking off from sea level- Hide quoted text -
>
> - Show quoted text -

The only reason I even opened this was because I couldn't believe it
was being re-addressed.....again. It's a non-issue for me, because:
1) The club instructors teach altimeter setting as it is presented in
the FARs, and 2) I've never seen an altimeter that could be adjusted
the nearly three thousand feet it would take to reach zero.

[Peter von Tresckow]

When R.A.S.is too quiet?

:-)

Pete

"Tom" <tomk...@yahoo.com> wrote in message
news:61432ac2-29db-4909...@z31g2000vbt.googlegroups.com...

[T]

Because then you would have no reason to attend the webinar!

[Tom]

As stated in the original message, I am still resolving issues with
FAA legal.
Caustic remarks aside, this is an issue with many pilots, and the
issue is more than the words used in the current regulation.

Tom Knauff

[Mike Schumann]

So once again, why not let us in on the response you have received
from the FAA?

[Tony]

> So once again, why not let us in on the response you have received
> from the FAA?

http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2012/Knauff.pdf

[T]

What issue is there to resolve?
Unless they contradicted 91.121(a)(1)(III)

In the west, you cannot roll the altimeter down to zero, the knob does
not adjust that far.
And if you depart from an airfield at 1200MSL, and roll the altimeter
to zero, you have to remember that you are reading 1200ft low, and
when you climb through 16,800 as read on the altimeter, you just
busted Class A !

We are under a Class B shelf, roll the altimeter down to zero, how do
you know where your citing is as you climb under the shelf? BUSTED!

T

[T8]

On Jan 26, 10:41 pm, Tony <abcon...@gmail.com> wrote:
> > So once again, why not let us in on the response you have received
> > from the FAA?
>

> http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adju...


Thanks Tony. I like my drama and my federal regulations as widely
separated as possible.

-T8

[Roy Clark, "B6"]

After more than 20 years as a forensic expert in my profession, I can
firmly state your
drama and your federal, state, county, local and any other regulations
are hardly
ever separated.

[Bill Palmer]

There of course, is no prohibition against having two altimeters. One set to QNH (field elevation) the other set to QFE (zero on the ground). This is how American Airlines operated for decades. QFE is also the standard in Russia and China.

[Martin Gregorie]

The Chinese must have some pretty special altimeters if this applies to
all their airfields, including those in Tibet: Bangda airport in eastern
Tibet is at 14,219 feet AMSL.

Bangda has an 18,000 ft (5500m) runway and, I gather, needs it. I've
heard that the pilots must be on oxygen for takeoff and landing.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[T8]

On Jan 28, 10:55 am, Martin Gregorie <mar...@address-in-sig.invalid>
wrote:

There's no need for any of this in soaring. XCSoar (what I use) and
all other GPS-map gizmos do a very good job of reporting AGL height
given a good 3D gps input and will (among other things) report an
estimated arrival height over any navpoint. We beat this to death.
The "AGL" altimeter guys had not a single compelling argument. They
lost.

-Evan Ludeman / T8

[Martin Gregorie]

I'm not supporting or dismissing the use of QFE settings (though its what
I was taught), just pointing out the impossibility of setting a standard
altimeter to QFE for every airfield in areas that the Chinese say are
part of China.

[T8]

On Jan 28, 11:31 am, Martin Gregorie <mar...@address-in-sig.invalid>

Got that. Not intending to pick on you Martin. FWIW, I was taught
QFE too. One of only two obvious defects in my otherwise excellent
primary instruction. The other was poor checklist discipline (augh,
how did that happen? that's another thread).

QFE is so wrong in so many ways... it's amazing to me that this keeps
popping up. I really don't give a fig about certain well known
friends of mine that insist on doing this despite the inevitable
communication problems "Xray Lima, say altitude" / "I'd rather not,
thanks" (:-)), but if there are still instructors teaching students
QFE, they really need to be taken to the woodshed and this needs to be
stopped.

-Evan Ludeman / T8

[glidergeek]

Can't believe you wasted the FAA's time on a question like that and
you brought it up here again.

[glidergeek]

On Jan 26, 4:33 am, Tom <tomkna...@yahoo.com> wrote:

If there is confusion it's because of an instructor not teaching
properly

This letter is in response to your July 19,2011 request for a legal
interpretation regarding
altimeter settings required in 14 CFR § 91.121. In your letter, you
state that there is
confusion among local area glider pilots as to whether altimeters must
be set to mean sea
level (MSL) when not using a cruising altitude, such as when
conducting student glider
flight training. Additionally, you indicate that glider operators are
unsure if the regulation
requires altimeters to be set to mean sea level (MSL) or above ground
level (AGL) during
student training and local flying.
The cruising altitude of an aircraft below 18,000 feet MSL shall be
maintained by
reference to an altimeter that is set to the current reported
altimeter setting of a station
located along the route of flight and within 100 nautical miles of the
aircraft. If there is no
such station, the current reported altimeter setting of an appropriate
available station shall
be used. In an aircraft having no radio, the altimeter shall be set to
the elevation of the
departure airport or an appropriate altimeter setting available before
departure. 14 CFR §
91.121(a)(1).
The cruising altitude is the MSL altitude or flight level maintained
during en route level
flight. For aircraft such as gliders, transient periods oftime at a
particular altitude do not
relieve pilots from the requirements to operate the aircraft in
reference to an altimeter that
is set according to the requirements of § 91.121(a). Thus, local area
glider pilots must set
their altimeters to MSL, not AGL, during glider operations, including
student glider
training flights.
Further FAA guidance on altimeter settings for glider operations can
be found in the Glider
Flying Handbook, FAA-H-8083-13, Chapter 4 (available online at
http://www .faa. gov/library/manuals/ aircraft! glider handbook/media/
faa-h-8083-13. pdf

[Martin Gregorie]

On Sat, 28 Jan 2012 09:16:27 -0800, T8 wrote:

> QFE is so wrong in so many ways... it's amazing to me that this keeps
> popping up. I really don't give a fig about certain well known friends
> of mine that insist on doing this despite the inevitable communication
> problems "Xray Lima, say altitude" / "I'd rather not, thanks" (:-)),
> but if there are still instructors teaching students QFE, they really
> need to be taken to the woodshed and this needs to be stopped.
>

Understood.

FWIW I carry two altimeters, a standard mechanical one and my SDI C4 vario
which is also an altimeter. I normally set the mechanical to QFE and the
C4 to 1013mb. This works well since my local airspace designations are
split roughly 50:50 between height AGL and flight levels with a slight
excess of AGL.

We're taught to ignore the altimeter in the circuit in favour of looking
out the window because this is all that works for a field landing, just
as all UK glider landings are effectively short-field landings for the
same reason. Further, very few glider fields share with GA so what the
altimeter has to say around the airfield is unimportant: its interesting
to see how high the winch launch was and if you're well above winch
height if you want to cross the field but that's about it.

[Dan Marotta]

I was never confused until reading this thread...

The only valid use I can think of for using QFE is for low-level airshows,
e.g., inverted robbon cut.


"glidergeek" <r.b...@sbcglobal.net> wrote in message
news:a22dba2d-cb3a-4192...@t2g2000yqk.googlegroups.com...

[guy]

The one situation where setting the altimeter to "zero' before flight
makes sense is flying a purely aerobatic flight. You will never be
towed high enough to bust airspace rules. You must be totally focused
on how high you are above the ground and to make sure you do not bust
the 1,500 floor for aerobatic flight. With so much going on in the
cockpit, setting the altimeter to zero makes the scan of the panel
very simple.

[Jonathon May]

I am coming to this thread late , but when I started we set QFE because we

only winch launched to 800ft and timed the flight in minutes and
seconds,you
new where you were going to land and when. Every thing has changed for me
,I now won,t rig if it is not soar able and always fly QNH ,but I still
like QFE
set for the first 3or4minutes till I am sure the rope isn't going to
break.But
then it,s a different world now the LX has QNH and AGL on the screen and
All
you need to do is re-set off tow.It is still nice to have QFE set for your

competition finish and I will re-set especially if control is giving it as
you call
5 minutes.

[Martin Gregorie]

Its also quite comforting if you're a flat-land flier and visiting a hill-
top site for a spot of ridge soaring.

[T8]

> It is still nice to have QFE set for your
> competition finish and I will re-set especially if control is giving it as
> you call 5 minutes.

I don't get this at all. What is the advantage?

Aerobatics and local winch ops have the common feature that one
doesn't expect to be sharing airspace with other users. In this case,
it doesn't matter to others what you use for an altimeter setting.

When sharing airspace with others -- which is most of recreational and
virtually all of competition soaring -- it's stupid not to have
everyone on a common standard. This is just as true when local
soaring around a public use airport as it is for cross country.

-Evan Ludeman / T8

[T]

Now that the webinar is over. What is Tom's take on all this?
Tom, do you set to zero, or actual field elevation prior to launch?
And why continue the discussion with the FAA.
91.121 is the rule with no exceptions.
We should be teaching our students the proper way and get them
ingrained to do the mental math to compute AGL from an MSL altimeter
from day one!

T