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MSL vs. AGL (Again)



 
 
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  #31  
Old July 17th 11, 03:44 AM posted to rec.aviation.soaring
T[_2_]
external usenet poster
 
Posts: 187
Default MSL vs. AGL (Again)


Oh boy...this sounds serious.

Why is the altimeter involved in the landing in any way in the pattern?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarmhttp://tinyurl.com/yb3xywl


AGREED!, today on a rough thermal tow day with thermal induced
turbulance and slack lines on tow, and after my student had a great
"learn to center the thermal and climb" day, just sitting quiet in the
back seat and let him learn by doing, toughest thing an instructor has
to do. Then some review of all the stalls down to pattern and landing.

On the second tow, just as we reached 2K AGL, on an MSL set altimeter,
I took control of the glider on tow and gave him two suction cups to
cover the altimeter and airspeed. As soon as they were set, I pulled
the release, turned off tow and "Your airplane". He tripped into a
thermal and climbed, and then I said, let's go home. Determining
pattern altitude entry based on what it looks like, controlling
airspeed by pitch reference to the horizon and sound of the wind over
the canopy. An excellent pattern and landing.

He is ready to solo.
T
  #32  
Old July 17th 11, 03:03 PM posted to rec.aviation.soaring
jim archer
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Posts: 21
Default MSL vs. AGL (Again)

On Jul 16, 11:30*am, Chris Donovan wrote:
On Jul 15, 9:57*pm, "John Godfrey (QT)"
wrote:





On Jul 15, 9:37*pm, Eric Greenwell wrote:


On 7/15/2011 1:16 PM, T8 wrote:


On Jul 14, 10:20 pm, *wrote:
The MSL/AGL issue has come before the Caesar Creek Soaring Club Board
once again. Not only has the Club been thrown into turmoil again, this
time it has specifically affected our instructors and how to most
effectively teach our students. I am curious if there are other Clubs
or organizations that teach using AGL.
Rolf Hegele
Member of the Board


Is there even *one* good argument for setting the altimeter to zero on
the runway?


You live anywhere in Florida?


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)


I still think there is hope... Consider (from Wikapedia)


Railway time was the name given to the standardised time arrangement
first applied by the Great Western Railway in England in November
1840. This was the first recorded occasion when a number of different
local times were synchronised and a single standard time applied.
Railway time was progressively taken up by all of the other railway
companies in Great Britain over the following two to three years. The
times schedules by which trains were organised and the times train
stations clocks displayed was brought in line with the local time for
London or "London Time". This was also the time set at Greenwich by
the Royal Observatory, Greenwich which was already widely known as
Greenwich Mean Time or (GMT).


The development of railway networks in India around 1860,[1] and North
America in the 1850s,[2] as well as other countries in Europe, also
prompted the introduction of standard time systems influenced by the
specific, geographical, industrial development and political
governance appertaining.


The key purpose behind introducing railway time was twofold. Firstly,
to overcome the confusion caused by having non-uniform local times in
each town and station stop along the expanding railway network and
secondly, to reduce the incidence of accidents and near misses which
were increasingly occurring as the number of train journeys increased.


The railway companies sometimes faced concerted resistance from groups
of local people in a number of places where trains stopped, who
refused to agree to adjust their public clocks to bring them into line
with London Time. As a consequence two different times would be
displayed in the town and in use with the station clocks and published
in train timetables differing by several minutes from that on other
clocks. Despite this early reluctance, railway time rapidly became
adopted as the default time across the whole of Great Britain although
it still took until 1880 for the government to legislate on the
establishment of a single Standard Time and a single time zone for the
country- Hide quoted text -


- Show quoted text -


Generally by the time a pilot gets about a hundred hours or so this
discussion resolves itself! * Which is about the amount of time it
takes when most Sailship pilots begin to wander from home field
anyways....did you like the "sailship pilots" word I just thought
up? * *Teach what the student can absorb at the time, and newbies need
to absolutly know where they are in reference to the ground and not
making mental calculations at every turn in the pattern! Additionally
teach common sense first, keep your ****ing head on a swivil and out
side of the cockpit not playing with computers and vario's at critical
moments.- Hide quoted text -

- Show quoted text -


Intelligent. And... During the first instruction flight, and all
other instruction flights for that matter, the student doesn't NEED to
know anything, that is what the instructor is for. If the student
cannot handle a particular task, say MSL altimeter calculations for
example, then don't teach it at all until they can. Then, when they
have learned ALL of the required skills they are ready for solo.
  #33  
Old July 17th 11, 05:43 PM posted to rec.aviation.soaring
T[_2_]
external usenet poster
 
Posts: 187
Default MSL vs. AGL (Again)

On Jul 16, 5:11*am, Burt Compton - Marfa wrote:
Now operating at Marfa, Texas (elevation 4849' MSL),


Respectfully,
If you are flying out of Marfa Texas, you cannot set "0" for AGL
flying.
The altimeter does not unwind that far.

T
  #34  
Old July 19th 11, 04:21 PM posted to rec.aviation.soaring
Chip Bearden[_2_]
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Posts: 93
Default MSL vs. AGL (Again)

Is there even *one* good argument for setting the altimeter to zero on
the runway?

-Evan Ludeman / T8


I learned how to fly at Caesar Creek Soaring Club (nee Soaring Society
of Dayton operating out of Richmond, Indiana) in 1965. As now, the
club used an altimeter setting of zero on the runway (AGL/QFE). I did,
too, for years--with a lot of cross country hours--because I flew only
in the Midwestern U.S. where the greatest difference between takeoff
and landing altitude was a few hundred feet. I referred to those
quaint Sectional charts we used for navigation back then to look up
the field elevation at other airports, which I would have done anyway
even if using MSL/QNH. There was a lot less controlled airspace so I
almost never talked a tower, ATC, or powered aircraft. Most of the
time, the altimeter told me about how high I was above the terrain. If
it looked closer, I used judgment to gauge when it was time to land,
just as I do today.

I can't remember when I made the switch to MSL/QNH for all the right
reasons. It wasn't a big deal. I'm sure using AGL/QFE was easier when
I was an early student--one less thing to worry about--but that's
something the instructor could have covered for me until I could
learn, just as he compensated for my poor takeoff and landing skills
initially.

The biggest reasons AGAINST switching to MSL/QNH earlier were,
interestingly enough, related NOT to staying around the home airport
but to flying cross country and, especially, contests:

1. Start and finish gate altitudes were set AGL. In the olden days
when we dove at high speed across a line on the ground, it was
slightly easier to judge how far above or below the max height one
might be when the big hand on the altimeter was unwinding towards zero
and the hand on the ASI was hovering near redline (ah, the good old
days....).
2. Final glides were MUCH easier to monitor. In those pre-computer
days, I would sit in the cockpit with my cardboard calculator in my
left hand monitoring landmarks as I flew on and comparing altitude
needed with actual altitude above the finish line read directly from
my altimeter. No subtraction required.

After I made the switch to MSL/QNH, for a while copied a technique I'd
read about some pilots using at the Worlds: i.e., I set my altimeter
on zero on the grid and wrote down the pressure setting, then
immediately set it back to field elevation. On final glide, I would
reset the altimeter to the zero pressure setting (AGL/QFE) again so I
could monitor altitude above the finish line. That worked well until I
started flying out West where, as some have pointed out, higher field
elevations made it impossible to reset the altimeter to zero. I read
of at least one world-class pilot who installed two altimeters in the
cockpit, one set to AGL/QFE and the other to MSL/QNH!

With the advent of final glide computers, I no longer needed my
cardboard calculator. I still carry it in the cockpit, however, and
occasionally pull it out to "common sense" the numbers coming out of
the computer. When I do, I mentally do the subtraction to determine my
actual altitude above the goal and am thankful for all the technology
that makes this decision such a no-brainer to younger pilots.

Chip Bearden
ASW 24 "JB"
USA
  #35  
Old July 19th 11, 08:10 PM posted to rec.aviation.soaring
Tom Stock
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Posts: 14
Default MSL vs. AGL (Again)

N11rdbird wrote:
The MSL/AGL issue has come before the Caesar Creek Soaring Club Board
once again. Not only has the Club been thrown into turmoil again, this
time it has specifically affected our instructors and how to most
effectively teach our students. I am curious if there are other Clubs
or organizations that teach using AGL.
Rolf Hegele
Member of the Board


I was taught that it is up to the. pilot in command. When flying around
the local airport, agl zero is fine. when flying cross country, MSL zero
is standard practice but not necessarily reliable since you do not know
where you will be landing.
  #36  
Old July 19th 11, 09:30 PM posted to rec.aviation.soaring
Eric Greenwell[_4_]
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Posts: 1,939
Default MSL vs. AGL (Again)

On 7/19/2011 12:10 PM, Tom Stock wrote:
wrote:
The MSL/AGL issue has come before the Caesar Creek Soaring Club Board
once again. Not only has the Club been thrown into turmoil again, this
time it has specifically affected our instructors and how to most
effectively teach our students. I am curious if there are other Clubs
or organizations that teach using AGL.
Rolf Hegele
Member of the Board


I was taught that it is up to the. pilot in command. When flying around
the local airport, agl zero is fine. when flying cross country, MSL zero
is standard practice but not necessarily reliable since you do not know
where you will be landing.


You've stated a couple of things in ways that aren't familiar to me.
What does "MSL zero" mean? Or maybe you meant "set it to field
elevation"? And why would it be more reliable if you knew where you were
landing?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
  #37  
Old July 19th 11, 10:23 PM
RAS56 RAS56 is offline
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First recorded activity by AviationBanter: Dec 2010
Posts: 85
Default

Believe it or not, a major American airline flew using what I would label as "blended" QFE procedures for departure, approach and landing until ~mid 90's. Three altimeters in the cockpit, the one's directly in front of the pilots would be reset to QFE below approx. 10,000 AGL, the center would be used to comply with ATC clearances in MSL.

The logic given for QFE use was to "standardize" the CAT I ILS Decision Height for EVERY airport flown into 200' AGL and to enhance altitude awareness above terrain.

Special altimeters were installed to allow the extra adjustment needed to fly into high altitude airports such as ABQ, DEN, JAC and the like.

The company transitioned over to QNH in the 90's to standardize with the industry and save $$$ on the altimetry costs and training.

As you can imagine, it made for some interesting instrument crosschecks inflight and puzzled looks when guests jumpseated in the cockpit.

Thanks for the trip down memory lane....

Rob

ps-teaching "ab initio"...QFE procedures...in today's airspace and traffic environment...does a disservice to the student and is potentially dangerous.

My 2 cents...

Last edited by RAS56 : July 19th 11 at 10:25 PM.
  #38  
Old July 20th 11, 03:51 AM posted to rec.aviation.soaring
Bruce Hoult
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Posts: 961
Default MSL vs. AGL (Again)

On Jul 20, 3:21*am, Chip Bearden wrote:
After I made the switch to MSL/QNH, for a while copied a technique I'd
read about some pilots using at the Worlds: i.e., I set my altimeter
on zero on the grid and wrote down the pressure setting, then
immediately set it back to field elevation. On final glide, I would
reset the altimeter to the zero pressure setting (AGL/QFE) again so I
could monitor altitude above the finish line.


I've only done a couple of comps, and in a low performance glider
(PW5) but something I thought obvious, and found useful, was to
annotate the task sheet before launch with the MSL height needed at
the last few turnpoints for a final glide at McCready 0, 2, or 4. And
maybe also at a few landmarks along the way. I also wrote down the
distance to run from each turnpoint.

There was one day that absolutely died, but I managed to get one final
slow scratching climb and then final glide at M=0 (with a 500 ft
safety height) from 3 turnpoints out. Which, to be fair, was only
about 50 km.
  #39  
Old July 21st 11, 02:48 AM posted to rec.aviation.soaring
Tom Stock
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Posts: 14
Default MSL vs. AGL (Again)

Eric Greenwell wrote:
On 7/19/2011 12:10 PM, Tom Stock wrote:
wrote:
The MSL/AGL issue has come before the Caesar Creek Soaring Club Board
once again. Not only has the Club been thrown into turmoil again, this
time it has specifically affected our instructors and how to most
effectively teach our students. I am curious if there are other Clubs
or organizations that teach using AGL.
Rolf Hegele
Member of the Board


I was taught that it is up to the. pilot in command. When flying around
the local airport, agl zero is fine. when flying cross country, MSL zero
is standard practice but not necessarily reliable since you do not know
where you will be landing.


You've stated a couple of things in ways that aren't familiar to me. What
does "MSL zero" mean? Or maybe you meant "set it to field elevation"? And
why would it be more reliable if you knew where you were landing?


Sorry, typing on my iphone, made a few edits but did not proof read it
again..
 




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