Altimeter Setting

On May 31, 11:22*pm, Greg Arnold wrote:
On 5/31/2010 8:06 PM, ContestID67 wrote:



He then takes a tow to what he thinks is 3,000 feet AGL but is only
really at 2,000 feet AGL. *The tow pilot doesn't think much about it
as people get off tow early all the time. *About to enter the pattern
the AGL'er thinks, "Gee, the ground seems to be kind of large
today ... but I am still at 1500 feet AGL so I'm must be OK." *He then
almost lands short as he was 1,000 feet lower than he thought. *End of
story? *Nah.

The poor guy couldn't tell the difference between 500' AGL and 1500' AGL
by looking out the window? *Sounds like it was time to retire his wings..

Here's a good one. I usually fly out of a busy general aviation
airport right on the edge of Class C airspace. We are surrounded by
mountains, talk to power planes and controllers, and fly cross country
a lot, so we always use MSL. Recently I spent a sunny afternoon down
at the local gliderport where they do a lot of training. I took a tow
to the ridge and got off at about 3,200 (MSL). Much later that
afternoon, the owner was up flying so I asked someone what I owed for
the tow. They asked me how high I went and I said "3,200 feet." A
quick look at the handy chart on the wall told me what I owed them for
"3,200 feet" and I happily paid and left. On the drive home I was
musing about how the price of tows was always going up, but who cares
when the planes and gadgets cost so damned much. Then it hit me WHY
they were going up. The gliderport uses AGL for training AND to
calculate the tows to simplify the billing, and I hadn't deducted the
field elevation when I told him "3,200 feet." I had bought about 800
feet of it sitting at the end of the runway waiting to hook up. All
I could do was laugh at myself, and they are welcome to the tip for
all they do for all of us. At least I hadn't scratched around cross
country for two hours with my gear down like I usually do... Now THAT
****es me off!

Don

In article
,
ContestID67 wrote:

We did have one incident related to the AGL/MSL switch that might be a
good to read about. One day yours truly flew a club ship and set the
altimeter to MSL. The next pilot was an die hard AGL'er. The AGL'ers
were used to finding the altimer not quite at zero due to barometric
changes and would "tweak" the altimeter to zero at the start of each
flight. Our field elevation is 888 feet. So the next pilot tweaks
the altimeter to "zero" but instead of subtracting 888 feet (by moving
the hands CCW), he tweaks it CW and adds 112 feet! Can you see where
this is going?

I did pretty much the same thing in my MSL-only club. Atmospheric
pressure had changed by 6-700ft from the last time the plane had flown,
and I did the nearest-thousand thing you describe. Even better, I
actually managed to do this twice in a row in our ASK-21! Discovered it
when I got off tow. Casually asked my passenger what his altimeter said,
and this discovered I'd managed to screw up both of them. Easy fix in
the air once I realized what I'd done.

Watch that thousands hand when you set your altimeter, and know what
your altitudes look like outside the cockpit!

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

Thorndike's Law of Primacy

Things learned first create a strong impression in the mind that is
difficult to erase. For the instructor, this means what is taught must
be right the first time. For the student, it means that learning must
be right. “Unteaching” wrong first impressions is harder than teaching
them right the first time. If, for example, a student learns a faulty
technique, the instructor will have a difficult task correcting bad
habits and “reteaching” correct ones.

The student's first experience should lay the foundation for all that
is to follow. What the student learns must be procedurally correct and
applied the very first time. The instructor must present subject
matter in a logical order, step by step, making sure the students have
already learned the preceding step. If the task is learned in
isolation, is not initially applied to the overall performance, or if
it must be relearned, the process can be confusing and time consuming.
Preparing and following a lesson plan facilitates delivery of the
subject matter correctly the first time.

On May 31, 10:07*pm, Rolf wrote:
Over the years (30 or so) Caesar Creek Soaring Club has vacillated
with setting the altimeter to zero or MSL. Last year the Board decided
to put the Club ships on an MSL basis (private gliders exempted).
There are however a number of members who are continuing to make it an
issue. I would be interested in your thought and comments.
Thanks
Rolf Hegele
CCSC President

Teach the kids to fly msl. Maybe that'll shame the old codgers into
doing it right.

Taking off to find that you have mis-set or not set the altimeter is
to find out that your check list discipline needs work.

I get a chuckle at every contest I go to. I can always find at least
one altimeter set to zero. Only some of those pilots are from
Ohio :-).

-Evan Ludeman / T8

On May 31, 10:07*pm, Rolf wrote:
Over the years (30 or so) Caesar Creek Soaring Club has vacillated
with setting the altimeter to zero or MSL. Last year the Board decided
to put the Club ships on an MSL basis (private gliders exempted).
There are however a number of members who are continuing to make it an
issue. I would be interested in your thought and comments.
Thanks
Rolf Hegele
CCSC President

The very fact that some people are having an issue should show how
limiting it is being trained to use QFE ( altimeter = 0 at the
field ). Tom's citing the law of primacy is a very good reason the
start the new students to use MSL altitude from the first flight.
Thousands of power students do it all the time. If a power pilot can
do it, then a glider pilot can.

On May 31, 10:07*pm, Rolf wrote:
Over the years (30 or so) Caesar Creek Soaring Club has vacillated
with setting the altimeter to zero or MSL. Last year the Board decided
to put the Club ships on an MSL basis (private gliders exempted).
There are however a number of members who are continuing to make it an
issue. I would be interested in your thought and comments.
Thanks
Rolf Hegele
CCSC President

I'm glad this issue came up. I am a new glider pilot (I soloed about
a year ago) and at my glider port, the students are generally taught
to set the altimeter to zero. I understand this is probably just to
reduce the task loading and also accidents due to miscalculations for
low time students. But when studying for the written exam there was
so much emphasis placed on MSL, I never understood why we simply set
the altimeter to AGL. Granted we are in Florida so there is not a
huge difference, but the difference is there none the less.

Seems counterintuitive unless you always expect to fly over the
airport. I suppose I should spend some time on the simulator and get
comfortable with doing it right.

Tom

start the new students to use MSL altitude from the first flight.
Thousands of power students do it all the time.

As do thousands of glider students, at least on this side of the pond.
The only situation we set the altimeter to QFE (i.e. zero on the ground)
is when we do serious aerobatics.

On 5/31/2010 8:07 PM, Rolf wrote:
Over the years (30 or so) Caesar Creek Soaring Club has vacillated
with setting the altimeter to zero or MSL. Last year the Board decided
to put the Club ships on an MSL basis (private gliders exempted).
There are however a number of members who are continuing to make it an
issue. I would be interested in your thought and comments.

Wearing my dry humor hat just a bit...

Do we U.S.-ers live in a democracy? If yes, then the preponderance of
replies-to-now suggests your club whiners are outvoted. ('We' don't, for
the seriously curious and unknowing, but that's another topic entirely...)

Is CCSC run like a democracy? (You poor devils...)

I learned at an 800' msl gliderport/general-aviation field, long ago and
far away. I remember my instructor's first preflight instruction; it
included setting the altimeter to 0'. I asked, "Why not to field
elevation?" He gave me the, "It's easier for your puny, overworked
brain," answer. I said, "OK," and got with the program. (It was the
first time I ever disagreed with my instructor, though...)

Eventually it was solo time. I did so without breaking anything. Next
flight, Tom (my instructor, and not Knauff), hopped in back after I
preflighted and instructed me to set the altimeter to field elevation. I
asked, "Why?" He said, "Because now you're a fledged pilot, and real
pilots care how high they are above ALL the ground, not one single
airport in the entire United States." I'd cared all along, but I didn't
tell him so & silently complied. It confused me a nano-second or two
fretting about my 'new' pattern height while on tow, but I figured it
out and have never been confused since...well, about this particular
issue, I mean!

Fast forward to another mountain airport and another time... There I wuz
about to launch from a field at 8149' msl elevation, with a steenking,
howling crosswind of 20+ knots. Naturally, I didn't want to land right
off tow, so I decided I'd tow to 3,000' agl instead of my normal
2,000'...insurance against broken thermals and getting blown downwind
away from the only landable pace for miles around (i.e. the airport).

I pop off at what my poor overstressed brain said was 3000' agl, known
that instant to be an indicated 10,150' (I rounded up 'for safety's
sake'!), in a decent-feeling upwelling and begin grinding around,
keeping a beady eye on my drift relative to the field. I begin climbing
too, but for some reason I couldn't get comfortable as fast as I thought
my climb rate should be permitting...something about that lurking ground
bugged me. About 500' into my climb I realized it was because the ground
was WAY too close for being 3500' agl. Apparently my instructor had been
right about my 'puny overworked brain' all those years ago!

Or maybe I was just an idiot that particular day. Also, I like to think
I'd'a entered the pattern 'by eye' and not at 0' agl had that thermal
not worked for me.

Legality aside, use agl...*please!!!*

Flying's real safe so long as you don't inadvertently hit anything.
Though I don't know this for a fact, I'll bet my retirement that at
best, it'll be embarrassing to inadvertently hit the earth when your
'field level' altimeter suggests you're still OK.

Bob - sometimes 'common sense' isn't - W.

On Jun 1, 10:54*am, Bob Whelan wrote:

Legality aside, use agl...*please!!!*

Bob... I think you need another cup of coffee.

-Evan Ludeman / T8

On Jun 1, 8:54*am, Bob Whelan wrote:
On 5/31/2010 8:07 PM, Rolf wrote:

Over the years (30 or so) Caesar Creek Soaring Club has vacillated
with setting the altimeter to zero or MSL. Last year the Board decided
to put the Club ships on an MSL basis (private gliders exempted).
There are however a number of members who are continuing to make it an
issue. I would be interested in your thought and comments.

Wearing my dry humor hat just a bit...

Do we U.S.-ers live in a democracy? If yes, then the preponderance of
replies-to-now suggests your club whiners are outvoted. ('We' don't, for
the seriously curious and unknowing, but that's another topic entirely...)

Is CCSC run like a democracy? (You poor devils...)

I learned at an 800' msl gliderport/general-aviation field, long ago and
far away. I remember my instructor's first preflight instruction; it
included setting the altimeter to 0'. I asked, "Why not to field
elevation?" He gave me the, "It's easier for your puny, overworked
brain," answer. I said, "OK," and got with the program. (It was the
first time I ever disagreed with my instructor, though...)

Eventually it was solo time. I did so without breaking anything. Next
flight, Tom (my instructor, and not Knauff), hopped in back after I
preflighted and instructed me to set the altimeter to field elevation. I
asked, "Why?" He said, "Because now you're a fledged pilot, and real
pilots care how high they are above ALL the ground, not one single
airport in the entire United States." I'd cared all along, but I didn't
tell him so & silently complied. It confused me a nano-second or two
fretting about my 'new' pattern height while on tow, but I figured it
out and have never been confused since...well, about this particular
issue, I mean!

Fast forward to another mountain airport and another time... There I wuz
about to launch from a field at 8149' msl elevation, with a steenking,
howling crosswind of 20+ knots. Naturally, I didn't want to land right
off tow, so I decided I'd tow to 3,000' agl instead of my normal
2,000'...insurance against broken thermals and getting blown downwind
away from the only landable pace for miles around (i.e. the airport).

I pop off at what my poor overstressed brain said was 3000' agl, known
that instant to be an indicated 10,150' (I rounded up 'for safety's
sake'!), in a decent-feeling upwelling and begin grinding around,
keeping a beady eye on my drift relative to the field. I begin climbing
too, but for some reason I couldn't get comfortable as fast as I thought
my climb rate should be permitting...something about that lurking ground
bugged me. About 500' into my climb I realized it was because the ground
was WAY too close for being 3500' agl. Apparently my instructor had been
right about my 'puny overworked brain' all those years ago!

Or maybe I was just an idiot that particular day. Also, I like to think
I'd'a entered the pattern 'by eye' and not at 0' agl had that thermal
not worked for me.

Legality aside, use agl...*please!!!*

Flying's real safe so long as you don't inadvertently hit anything.
Though I don't know this for a fact, I'll bet my retirement that at
best, it'll be embarrassing to inadvertently hit the earth when your
'field level' altimeter suggests you're still OK.

Bob - sometimes 'common sense' isn't - W.

These days it'a mostly a non-issue. PDA-type glide computers, and
some built-in units, provide constantly updated AGL height since they
are loaded with a digital elevation map and know your GPS position.
Just make sure the local atmospheric pressure is set. Some even set
that for you at takeoff: (Hmm, GPS says I'm at BDU and we're not
moving so we must be on the ground which, according to my airport
database, is 5288' which means the station pressure is 29.92".)
Airborne, you can just listen to an AWOS to get station pressure.

BTW, that last bit, airborne altimeter setting, IMHO is the biggest
reason to set altimeters to MSL. Altimeters can only be set
accurately to MSL when airborne since that's the only station pressure
data anyone transmits. Professionals worked this out a long time
ago. It isn't up to us to figure out yet another way to do it.