MSL vs. AGL (Again)
N11rdbird
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
SoaringXCellence
Fred Blair
started taking lessons 25 years ago.
Fred Blair - CFIG
T
I don't think you have provided enough information to effectively
answer the question. However, I think I know where you are going.
TEACH MSL, to teach any thing else is a disservice to your students.
Most "eastern" clubs teach AGL. Setting the altimeter to zero altitude
and not to field MSL elevation. Powered airplane students are never
taught to do this, but to set the altimeter setting or field elevation
as per their respective manuals.
If you fly under the floor of class b airspace, how do you know when
to stop the climb to not violate the class b? Your field is at 1000
MSL, but you set "0". there is class b above you at 6000 MSL, but when
your altimeter says 5000 you are already violating the class b. Some
may argue to do the math and know that 5K on the altimeter is the
limit. BULL CRAP,set the altimeter correctly the first time and it
will read correctly with no math required.
And if your newly minted pilot ever comes out west, he'll never be
able to set to "0" or AGL, the altimeter does not "unwind" far enough.
If your newly minted pilot ever contacts any ATC facility for
transition around controlled airspace, the ATC will issue an altimeter
setting which he is expected to set and the report his altitude
accordingly. But now he is set to MSL and not AGL and he's never delt
with MSL before.
Your pilot is flying with others who are taught MSL, but his altimeter
is set to AGL. When they report locations and altitudes they are
expecting MSL and who is going to miss report or miss interpret? The
pilot set to AGL!!
Teach them right the first time and forget it!!
T
Sorry, I forgot to sign my post.
T, CFIG
Tony
i'd be interested to know what your AGL pilots think of FAR 91.121, it
applies to aircraft not airplanes. do they argue that since they are
not "maintaining" an altitude or flight level in their glider that it
doesn't apply to them? I don't buy that and i doubt the FAA would
either.
Eric Greenwell
This question suggest some members want to train pilots to only fly
locally and only at this club. Is that the intent of the training the
club provides? If the club wants the pilots to be able to fly
cross-country or from other airports, then teach them MSL from Day One,
and banish AGL settings.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl
- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz
GM
Our club flies out of a county airport with a lot of mixed traffic,
i.e. everything from large biz-jets down to home-built LSAs and
helicopters. We are talking to each other and therefore, the altitude
reporting has to be off the same base - MSL!
Uli Neumann
Tom
interpretation of the rule is?
They have been asked before - numerous times.
Tom
jsbrake
battle. However, we're getting more power traffic in the area, and
they report MSL. There has been some confusion, but we're working on
it.
One compromise that was made is that we set MSL, but created circle
stick-ons that fit around the altimiter to show various AGL heights:
Low tow (1250') and all thousands. The thousands needle points to the
AGL height indicator.
-John
Ralph Jones
wrote:
Teaching via AGL reduces confusion in one extremely limited context
and massively increases it everywhere else. It must be based on the
assumption that the students are much dumber than power students.
That said, my former home field, the old Black Forest, elevation 7180
MSL, took the idiocy even further: they taught students to set the
altimeter to 7000 for easy subtraction. You can imagine what it would
be like to fly XC that way...
rj
Bill D
Let me guess, those advocating AGL have no XC experience.
Yet another reason to require instructors to have at least minimal XC
experience. I've been pleased to hear some clubs are requiring their
instructors to have at least a Silver Badge.
Bill Daniels
Bill D
> x-c experience. One is John Lubon JL, a familiar face on the contest
> scene.....but sadly many don't. Oddly a number of instructors are
> retired professional pilots either in the military and commercial
> world.
>
> Gary Adams GA2
> CCSC member
It's sometimes the case that career airplane pilots don't take gliders
seriously enough.
If you want to see them sweat bullets, take one who is seeking to add
a -G to their CFI certificate out of gliding range of the home field
and ask, "Exactly how much altitude do we need to get back".
Suddenly, a correctly set altimeter becomes a big deal. I had to
remind one CFI who seemed not to be handling the situation well that
he could listen to AWOS to get a current altimeter setting.
Another situation where a difference in attitude shows up is the
simple question, "How far away would you be willing to fly right
now." This is asked at about 1200' AGL near the pattern IP. They
often indicate a point 4 or 5 miles away. (8-10 mile round trip)
Airplane pilots tend to be far more comfortable gliding away from the
runway at low altitudes than I am. I think this lack of concern leads
to at least some landing accidents.
I haven't done it yet. (I'm thinking about it.) If the candidate
points in a direction where there is a known-safe land-out field, I
may say, "Let's go - show me". Nothing like an unplanned land-out to
bring the altimeter setting (and altitude) issue into sharp focus.
T8
Is there even *one* good argument for setting the altimeter to zero on
the runway?
Post Mills Soaring Club is all QNH, all the time.
-Evan Ludeman / T8
John Smith
> Is there even *one* good argument for setting the altimeter to zero on
> the runway?
Aerobatics. ;-)
Other than that: no.
Andy
>If you want to see them sweat bullets, take one who is seeking to add
>a -G to their CFI certificate out of gliding range of the home field
>and ask, "Exactly how much altitude do we need to get back".
If you are out of gliding range the answer doesn't matter until you
find lift and then want to know when to leave it. Up to then the
correct response may be "You have control".
>Suddenly, a correctly set altimeter becomes a big deal.
Correctly set yes, but the problem can be solved whether it is set to
the correct QFE or set to the correct QNH. It's actually easier in
this case to use QFE since if the altitude needed is less that the
indicated altitude then you have a glide solution. No need to worry
about the value of field elevation. In the above I'm assuming that
altitude needed is the altitude expected to lost in making the glide
plus the arrival margin, not the absolute altitude. That, after all,
is what has to be determined first.
I'm not arguing for using QFE, just pointing out you have selected a
poor reason for not doing so.
Andy
ContestID67
Our club (http://skysoaring.com) asked people to fly MSL about 6 years
ago and then mandated it about 4 years ago in all club ships. We
marked the altimer "MSL ONLY Club Rules". If you are flying your own
ship, you are PIC and can do most anything you want, and suffer the
consequences too.
The reasons for MSL are simple;
1) The FARs require it.
2) Unless you are living in a dead flat area, the airport you launch
from and the airport you might land at will be at different
altitudes.
3) If you launch at an airport above 3,000ft or so you probably can't
set your altimeter to AGL in the first place.
4) If you desire to fly anything beyond gliders, you had better use
MSL as your instructor will kick you out of the airplane otherwise.
5) Go for a check ride with an examiner, fly AGL, and see what
happens.
Rule of primacy rules - the first thing you are taught should be the
right thing as whatever is taught is going to be doubly difficult to
be un-taught. MSL it is!
- John DeRosa
Bill D
Your objection only holds true if you manage to return to the
departure airfield. "Out of gliding range" implies the flight may end
somewhere else.
ContestID67
1) I might agree that for a brand new pilot that AGL may be easier to
learn, but that doesn't make it right, nor make sense in the long
run. Primacy, primacy, primacy.
2) Once you convert, go all the way - don't make it optional - half
measures can cause problems. Here is a scenario that happened to me
while we were in the "optional" mode. I flew a club ship and used MSL
(888ft). I land and another pilot jumps in and thinks, "Heck, the air
pressure must have changed so all I need to do is tweak the big hand
back to zero". So he reset the altimeter to AGL by turning the hands
CLOCKWISE. See where this is going? What he did was move the
altimeter setting by +112ft, not -888ft. So now the altimeter is at
1,000AGL, not zero AGL, but he doesn't notice. The other pilot gets
off tow at 2,000ft AGL (thinking he is at 3,000ft AGL). The tow pilot
notices the other pilot getting off 1,000ft early but doesn't think
much about it (until later). At some point the glider pilot thinks
something like, "Wow, things sure look big", promptly lands out and
dings the glider. A CFIG comes up to me afterwards and says, "You
should have reset the altimeter back to 0 AGL after your flight."
Huh? My comment was, "Who exactly is in command of the glider? Me
standing on the ground or the guy in the cockpit?" End of
conversation.
Name withheld for fear of bringing up bad memories in others....
Andy
>
> - Show quoted text -
No - your stated question was - "How much altitude do I need to get
back?", not "How much altitude do I need to landout?".
Andy
glidergeek
"Tonopah traffic Skywagon N180BM entering left down wind descending
out of 7200' ".
"Tonopah traffic glider N233L I'm left down wind midfield at (hmmm,
let's see the field is, ahh, where's my chart uh 5426'
uhhh I set my altimeter to 0' when I took off 30 minutes ago now it
says 1520' uhh plus 5426' is uhh, man I wish I had oxygen in this ship
I can't
add). Uhh I'm 1520' above the field, doh.
Ka boom.
Eric Greenwell
> On Jul 14, 10:20 pm, N11rdbird<ro...@att.net> 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?
John Godfrey (QT)
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
5Z
> "Tonopah traffic Skywagon N180BM entering left down wind descending
> out of 7200' ".
Better example would be to use Stewart Airport, about 3 miles away from Caesar Creek. Just ask one of the AGL proponents to describe the radio conversation between an airplane at Stewart and a glider at CCSC, as they're approaching each other on a collision course.
-Tom
T
Excellent analogy. But the mechanicals are not there to set an
altimeter to zero at Tonopah. It does not unwind that far. And if
you've flown around Tonopah, you know the valleys are around 5500MSL,
and the "ridges" can be above 11,000MSL.
Pilots need to do the math from day one. Fly on MSL, every one else
does. Learn to compute AGL from MSL minus
chart elevations below you.
T
T8
That would be a coincidence, not an argument :-).
Cripes, even my little podunk state of NH has 6288 feet of topographic
relief. I set my altimeter to the low point :-) (also a coincidence).
-T8
Burt Compton - Marfa
> On 7/15/2011 1:16 PM, T8 wrote:
> > Is there even *one* good argument for setting the altimeter to zero on
> > the runway?
>
> You live anywhere in Florida?
>
I used to. Silly me. When my flight school was in Miami at a small
grass airport, I had my airplane and glider students set the altimeter
to field elevation.
9 feet. Just a hair above zero. It was an attempt to help them
understand why MSL setting will be important in their future flying.
Now operating at Marfa, Texas (elevation 4849' MSL), I teach MSL
because a glider pilot will need 8,400' MSL to clear nearby Mount
Livermore and if they fly their Gold badge XC north in the direction
of Hobbs or Midland / Odessa they will see plus 3,000' MSL on their
altimeter, not minus 2,000' when they land.
What's the FAA "opinion"? Besides the FAR 91.121 (which contains the
vague term "cruising"), the flawed but "official" FAA Glider Flying
Handbook teaches to set an altimeter to MSL. See section 4-5,
"Setting the Altimeter." If that's the way the latest FAA
publication is teaching altimeter setting . . . that is something that
a legal mind might refer to in court after the accident.
Points to Ponder:
All airports are charted in MSL.
All obstacles are charted in MSL.
All terrain is charted in MSL.
Airplane pilots aloft in your airspace are setting their altimeters to
MSL.
Communications with ATC are in MSL.
Class A airspace starts at 18,000' MSL.
Restricted Airspace . . .
Why are we still debating this? Is the math that difficult? (Round
up, if it is easier.)
Burt
Marfa Gliders Soaring Center, west Texas (4,849' MSL)
USA
Guy Byars
> Better example would be to use Stewart Airport, about 3 miles away from Caesar Creek. Just ask one of the AGL proponents to describe the radio conversation between an airplane at Stewart and a glider at CCSC, as they're approaching each other on a collision course.
The radio conversation would be somewhat quiet. The CCSC club gliders
don't have radios and not many at Waynesville.even bother with radios.
BobW
> 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
Wowser!!! Thanks - I think - for providing me an "I can't believe what I'm
experiencing," moment. What a buzz.
But enough about me. The 'issue' you raise is akin to an argument about
whether it's better to verify a revolver is unloaded by cracking open the
cylinder and looking, or, leaving the cylinder in place and looking down the
barrel and possibly pulling the trigger if there's any doubt.
The people advocating setting to 0' are - to be blunt - arguably insane.
Paraphrasing (I think) Elmer Fudd, "What a bunch of maroons!!!" (Have any/all
of them contact me personally for a considered, polite, civil discussion of
why this is so.)
Amazement aside, thanks for exposing your club's issue to a public spotlight;
this sort of 'thinking' definitely needs to be excised from potential training
curricula.
Respectfully,
Bob W.
Chris Donovan
wrote:
>
> - 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 fucking head on a swivil and out
side of the cockpit not playing with computers and vario's at critical
moments.
Eric Greenwell
>
>
> 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!
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, Flarm
http://tinyurl.com/yb3xywl
T
> 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
T
> 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
Chip Bearden
> the runway?
>
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
Tom Stock
> 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.
Eric Greenwell
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?
RAS56
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...
--
RAS56
Bruce Hoult
> 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.
Tom Stock
Sorry, typing on my iphone, made a few edits but did not proof read it
again..