Altimeter Setting

On Jun 2, 10:14*am, "kirk.stant" wrote:

Everyone sufficiently confused now?

Too many "Qs". Who knows what they all mean anyway? There was one I
used to enjoy when in the cadet signals corps "Shall I point my
searchlight at a cloud, occulting if necessary, in order to pinpoint
my position". Don't use that much anymore but a variant appears in
the "abbreviations available for maritime mobile service" as QUQ.

See http://life.itu.ch/radioclub/rr/m1172.htm if you want fun read.

Andy

On Jun 2, 6:36*am, Tom wrote:
"Yeah, but as for 91.121 you're not maintaining any particular
cruising
altitude or flight level when operating a glider. "

The FAA legal department told me they recognize the problem /
confusion with the English language usage used in the regulation.
Gliders do not "cruise." However, the intent of the rule is clear.
Glider pilots must be aware of airspace altitude restrictions
including aircraft cruising.

Recognized exceptions to setting the altimeter to MSL include crop
dusting and aerobatics.

Yesterday, there was a very close near-miss with a glider and
commercial jet descending for a landing. The club where the glider
flies commonly uses and teaches using AGL altimeter settings.

It will only take *a very few of these encounters for gliders to be
required to have ADS-B transponders and perhaps be banned from certain
airspace near airports where larger aircraft fly altogether.

A new, highly accurate GPS satellite was launched yesterday. First of
a series leading up to the new transponder technology.

Tom Knauff


Thanks for the clarification of the FAA perspective on this. That and
just commons sense also says teach and use QNH, do instructors want
glider pilots to talk to other traffic?, to ATC when needed?, if there
is no other traffic or ATC locally, do instructors want pilots to have
the good foundation to do so when it would add to saftey? Do they want
pilots fixated on altimeter measurements in off-field landings (which
setting QFE may encourage), etc. Do they want new student pilots to be
heading towards flying XC or wasting time flying patterns? Start them
doing things properly and it won't need to be undone if those students
happen to blunder their way to a successful transition to XC flying.
It maybe is more a worry if there are DPE's out there that let a
student pass a check ride with QFE set. I know at some locations the
difference may not be noticed.

---

On the near miss, was they point that the glider pilot should have
been talking to ATC, and that QNH vs. QFE settings there a factor? Or
was the point something else?

If it was in an area of high density airline traffic then a good
option for the glider pilot would be to install a transponder.
Different ATC facilities are also very accommodating in terms of
working with gliders on flight following or similar procedures, most
would much rather hear from us than not.

Unfortunately Tom's post seems to confuse ADS-B and transponders.
Since we are facing lots of confusion sorting our the benefits,
issues, etc. with ADS-B I really want to avoid confusion on basic
points like this.

The new GPS satellite really has nothing directly to do with ADS-B,
although it will help improve GPS overall.

ADS-B is not a transponder. If using UATs there is no transponder
involved. If using 1090ES then the transponder is transmitting ADS-B
data but that's kind of an entirely separate function from it's role
as a transponder. Transponder literally means something that replies
to an interrogation. ADS-B is the reverse, the "A" means "automatic"
i.e. no interrogation. So strictly there is no such thing as an "ADS-B
transponder".

To my previous post in a separate thread on ADS-B, if the issue is
gliders flying in areas of high airline or fast jet traffic, that
traffic is very well equipped with TCAS II which can issue a
resolution advisory (RA) to help avoid the glider. TCAS II only can do
so if the glider is equipped with a Mode C or Mode S transponder. TCAS
cannot issue an RA against an ADS-B UAT equipped glider that does not
also have a transponder. Those airliners and fast jets may or may not
be able to display ADS-B UAT equipped glider traffic depending on
whether they have ADS-B CDTI capabilities on their traffic displays
(and again CDTI does not issue an RA, that's TCAS-II's jobs). There is
no requirement for anybody to equip with CDTI. As the FAA rolls out
ADS-B GBTs (Ground Based Transceivers==ground stations) ATC will see
ADS-B UAT traffic on their traffic displays. It is quite likely that
ATC radar will not see gliders today that are not transponder
equipped, and the GBTs will at least provide visibility of a UAT
equipped glider to ATC (and over a much larger airspace volume than
conventional SSR coverage). But without a transponder that last
fallback of TCAS-II won't work without transponders.

BTW I hope the ridge-running folks out there are trying to look at the
GBT coverage in areas they fly. That will give a good idea of the use
of ADS-B as a SAR/last know position tool. The other issue is going to
be a mixed environment of 1090ES and UAT devices on the ridges,
outside of GBT coverage to provide ADS-R (relay services) -- (e.g. at
points down low on a ridge) a Mode S transponder transmitting ADS-B
over 1090ES will not be seen by a UTA receiver and visa versa. The
only real solution I see there is dual-link receivers, luckily this is
not something terribly difficult, most of the work to do a UAT or
1090ES receiver is common, its just requires a bit more work, and
cost, to put both in one box.


Darryl

On 6/2/2010 11:54 AM, Andy wrote:
On Jun 2, 10:14 am, wrote:

Everyone sufficiently confused now?

Too many "Qs". Who knows what they all mean anyway?

Mama I don' wanna become a jargoon, so here's my query: can we agree to
quit with the "Q's"?

QED?

Bob - my coffee's fine - W.

On Jun 2, 1:32*pm, Bob Whelan wrote:
On 6/2/2010 11:54 AM, Andy wrote:

On Jun 2, 10:14 am, *wrote:

Everyone sufficiently confused now?

Too many "Qs". *Who knows what they all mean anyway?

Mama I don' wanna become a jargoon, so here's my query: can we agree to
quit with the "Q's"?

QED?

Bob - my coffee's fine - W.

Que? No comprendo!

66

On Jun 2, 12:32*pm, Bob Whelan wrote:
On 6/2/2010 11:54 AM, Andy wrote:

On Jun 2, 10:14 am, *wrote:

Everyone sufficiently confused now?

Too many "Qs". *Who knows what they all mean anyway?

Mama I don' wanna become a jargoon, so here's my query: can we agree to
quit with the "Q's"?

QED?

Bob - my coffee's fine - W.

QED, the meaning is in here
http://www.angelfire.com/va3/navy_mars/ACP131.pdf

Frank Whiteley

On Jun 2, 2:09*pm, Frank Whiteley wrote:
On Jun 2, 12:32*pm, Bob Whelan wrote:

On 6/2/2010 11:54 AM, Andy wrote:

On Jun 2, 10:14 am, *wrote:

Everyone sufficiently confused now?

Too many "Qs". *Who knows what they all mean anyway?

Mama I don' wanna become a jargoon, so here's my query: can we agree to
quit with the "Q's"?

QED?

Bob - my coffee's fine - W.

QED, the meaning is in herehttp://www.angelfire.com/va3/navy_mars/ACP131.pdf

Frank Whiteley

Here's how the Air Force dealt with the issue after the Thunderbirds
crash in '04.
http://www.avweb.com/avwebflash/briefs/186582-1.html

Craig

On 6/2/2010 2:21 PM, Craig wrote:
On Jun 2, 2:09 pm, Frank wrote:
On Jun 2, 12:32 pm, Bob wrote:

On 6/2/2010 11:54 AM, Andy wrote:

On Jun 2, 10:14 am, wrote:

Everyone sufficiently confused now?

Too many "Qs". Who knows what they all mean anyway?

Mama I don' wanna become a jargoon, so here's my query: can we agree to
quit with the "Q's"?

QED?

Bob - my coffee's fine - W.

QED, the meaning is in herehttp://www.angelfire.com/va3/navy_mars/ACP131.pdf

Frank Whiteley

Here's how the Air Force dealt with the issue after the Thunderbirds
crash in '04.
http://www.avweb.com/avwebflash/briefs/186582-1.html

Craig


It seems like a Thunderbirds show is one example of where AGL should be
used, but they continued to use MSL. Must be hard to use different
numbers for each show.

We can't set to "Zero" our MSL on the ground is higher than the altimeter
can adjust.

We train our students to "enter the downwind between 3800-3600 MSL (800-1000
AGL), then forget the altimeter. LOOK OUTSIDE

We cannot set "Zero", our MSL on the ground is higher than the altimeter can
adjust.

If the tow pilot cannot do mental math to call down the release height..
6400 release minus 2800 field elevation = 3.6 for the radio call then
perhaps the tow pilot is over tasked and should not be flying?
We cannot set "Zero", our MSL on the ground is higher than the altimeter can
adjust.

If we were to try to use zero... then how would our students or other
"trained pilots" know when they are bumping their heads on the Class B above
us defined by MSL, or if a transient traffic calls at a set altitude.. they
they may be at the same altitude and not 1000ft different?

We cannot set "Zero", our MSL on the ground is higher than the altimeter can
adjust.

A visiting pilot trying to set zero, will not be approved for local solo
flights until he can show proficiency at FAR required operations (91.121)

We cannot set "Zero", our MSL on the ground is higher than the altimeter can
adjust.


"kirk.stant" wrote in message
...
On Jun 2, 8:04 am, 150flivver wrote:
On Jun 2, 12:38 am, (Alan) wrote:





In article

150flivver writes:

On May 31, 10:14=A0pm, GM wrote:

Rolf, if memory serves me right, the FARs are clear about it:
setting
to MSL is required.

I don't recall any regulation requiring the altimeter to be set to QNH
unless the particular operation requires it (eg. an instrument
approach).

14 CFR 91.121 (aka FAR 91.121)

For extra credit, note 91.121(a)(1)(i) which says you must use the
setting
from the local radio source in preference to setting to the field
elevation.
As was pointed out in this group a couple years ago, the examiner in
the back
seat knows that regulation.

Alan

Yeah, but as for 91.121 you're not maintaining any particular cruising
altitude or flight level when operating a glider. I certainly agree
that cross country gliders should be operating off QNH but if you're
flying locally, you should have the option of setting QFE. I fly a
towplane and use QFE 99% of the time--any position calls I make I
convert to MSL (I have a table to reference on my legboard). If I
have to go and retrieve a landout, I'll use QNH.- Hide quoted text -

- Show quoted text -

Interesting. I also fly a towplane for a club and use QNH exclusively
- so when I call the glider release, it's MSL and doesn't need any
conversion (and associated potential for mistake). That call is a
safety-of-flight issue, IMHO - and not only for local club traffic,
but for any other aircraft passing by - and much more important than
reporting the tow height to the ground for billing purposes (which, in
our club, is not a tow pilot responsibility anyway - the member logs
it after the flight or gets charged a flat 3k ft tow...). As chief
tow pilot I don't want my tow pilots doing anything during their tow
flight that takes them away from clearing their flight path,
especially with lots of gliders milling around!

Kirk
66

On Jun 2, 8:17*am, T8 wrote:
On Jun 2, 7:47*am, "
wrote:





Just to play devil's advocate on this "zero altimeter" thing.........

Here is a scenario.....

Your kid is running in a one mile track race........you want to time
the race.......

The race begins.....you look at your watch....the time is 12:30:
26.010

As your kid crossed the finish line you look again at you
watch...........12:35:49 070

How fast did the kid do the mile?

Now, when my kid starts the race, I had my watch set at 0:00:00.000

At the finish it reads.......5:23.060..........done! no math!

Altimeter is a TOOL.......tool's are for the ease of use of the
user.......My tools work for me, I don't work for my tools. Tools can
be used in different ways for different purposes. *Using MSL on the
altimeter does serve a good purpose for many situations, but not
all........

Cookie

Cookie

So what do you do when on a XC flight, not particularly high, and
encounter class D airspace that you'd like to fly over?

-T8- Hide quoted text -

- Show quoted text -

Interesting question.....
First of all, I recommend MSL altimeter setting for X -C flight.

Second, if I'm going to fly OVER the Class D.....I won't do anything
in particular.........

Third, If I am going to ENTER the Class D, I will contact via two way
radio

Forth, Class D is often defined using the "AGL" datum....Class D is
typically 2500' AGL over the airport in question.

Fifth, the class D is depicted on the chart in MSL

Sixth, If for some unknown reason, my altimeter was set to zero at
take off instead of 372' (msl of my home airport) I would simply add
400 to my indicated altitude, or get the altimeter setting along the
way.

Seventh, since the class D (if typical) is 2500 AGL, and I took off
from that airport at altimerer zero, then I would know whether I was
in, or over, the airspace easily......

Cookie

On Jun 2, 12:10*pm, "kirk.stant" wrote:
On Jun 2, 6:39*am, "
wrote: On Jun 2, 7:16*am, Cats wrote:

...Also MSL is not the

"datum" used in collision aviodance.
Cookie

Uh, wrong. *When you report your altitude over the radio, you are
going to read it off the altimeter, and if you are below 18,000ft (in
the US) it should be set to QFE for the closest reporting point.

So when someone calls out that he is "Eastbound over Littletown at
7300ft" on a hazy afternoon, and you are westbound over Littletown,
staring into the sun, at 7400ft, you had better hope he is using the
correct altimeter setting! *Cuz that's how you are going to check to
see if you have altitude deconfliction (since I doubt you have TCAS in
your glider).

You are correct that transponders use pressure altitude when
reporting, but that is a different issue - you don't normally use raw
Mode C altitude data in the cockpit for altitude deconfliction - and
ATC applies a correction when reporting traffic altitude over the
radio.

My .02$: *QFE can be useful for low altitude aerobatics - for an
airshow pilot who performs at a lot of different locations. *That's
about it, since the advent of radio altimeters and GPS. *Otherwise,
QNH is what should be used (and it's arguably required by the FARs),
from the very beginning. *I don't want to share airspace with someone
who can't do the math and needs the altimeter to know when to turn
Base and Final! (Hint - if you are really math-in-the-cockpit
challenged, write the darn pattern altitude on the back of your
hand!).

Kirk
66

Transponders and PCAS, and TCAS all use Pressure altitude as the
reference, not MSL......It has to be "translated" later by somebody or
something........Class A uses ony pressure altitude....

Just pointing out there is more to the story! There are many datums
for altitude...........Any one is translatable to another.......Just
add or subtract.

Don't you think all this "Q" crap really confuses the issue? Why not
use real English words? Q for altitude? Go Figure!

Cookie