GPS Altitude with WAAS

On Mon, 29 Sep 2003 17:17:49 GMT, David Megginson
wrote:

Roger Halstead writes:

OTOH with those temperatures we either have severe clear, or blowing
snow. It's rather uncommon to see clouds near the ground when it's
that cold here in the flat lands.

Maybe it's just not cold enough. Once you get past -30 degC or so,
you can get a dense freezing mist (like smoke) rising off any open
water, like a lake or wide river -- the parts that are frozen over
start to make a creepy, moaning sound.

I agree that truly cold temperatures ( -20 degC) tend to mean VMC, at
least where I live -- it's one of the fantastic things about winter
flying (clear skies, excellent visibility, good climb performance,
minimal turbulence, high ground visibility at night, and early sunsets
that make it easy to stay night-current). The downsides are having to
plug in the engine heater overnight and dealing with the @#$%#@ wing

I have a couple layers of the new blankets sewn together to fit around
the entire front of the plane from mid windshield forward around the
engine compartment and underneath where it completely covers the nose
gear doors, and around the front to wrap the first quarter of the
prop. The back of the spinner is even warm.

Problem is...the Deb doesn't warm up till I'm at cruise, or duri8ng a
long climb to altitude.

You can actually stay comfortable in heavy slacks and a long sleeve
shirt, but that is *after* climb out. :-))

Getting the Cub Cadet with snow blower out, cleaning the ramp and
maybe even part of the taxiway does not make the inside of the plane
feel any warmersigh It's kinda like working in an unfinished house
in the winter. Man, but it gets cold in there.

I've flown from Michigan to Gainsville Ga (LGM) without seeing a
cloud. Then again, I've flown from the middle of Tennessee and not
seen the ground till some where around Jackson Michigan.

Unlike the summer storms, you can fly over a blizzard at some where
between 3000 and 5000 AGL. The winter storms seldom get very high.
But I have been sitting "up there" and after hearing some of the
conversations on UNICOM thinking it'd be real nice to have one more
fan. That was when I realized it's a good idea to not only have a way
out, but have a way down when single engine. If it's really cold you
don't have to worry about ice in the clouds either, but since then I
make it a point to try to stay near the edges of those big storms when
there is no safe way down.
covers.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

All the best,


David

Roger Halstead writes:

Problem is...the Deb doesn't warm up till I'm at cruise, or duri8ng a
long climb to altitude.

You can actually stay comfortable in heavy slacks and a long sleeve
shirt, but that is *after* climb out. :-))

The heat in my Warrior is more than sufficient to keep the cockpit
warm enough for no coat or gloves at -30 degC OAT once I'm flying (I
have to turn it down quite a bit), but then, in the winter I'm always
wearing an extra layer of socks and thermal underwear just in case.
One of my favourite ways to fly in the winter is to open the overhead
vent a bit *and* pump the heater up to full, but that's probably just
strange.

Getting the Cub Cadet with snow blower out, cleaning the ramp and
maybe even part of the taxiway does not make the inside of the plane
feel any warmersigh It's kinda like working in an unfinished house
in the winter. Man, but it gets cold in there.

I pay more than some people (CAD 65/month =~ USD 47/month) for an
outside tiedown on the grass, but since my tiedown happens to be at a
major airport (CYOW), I have the benefit of its services, like two ILS
approaches and good snow removal.

Unlike the summer storms, you can fly over a blizzard at some where
between 3000 and 5000 AGL. The winter storms seldom get very high.
But I have been sitting "up there" and after hearing some of the
conversations on UNICOM thinking it'd be real nice to have one more
fan. That was when I realized it's a good idea to not only have a way
out, but have a way down when single engine.

This will be my first winter flying with my instrument rating, so I'll
have a lot of learning to do. Last winter, when I was doing the IFR
training, we couldn't find IMC no matter how hard we looked.


All the best,


David

: The heat in my Warrior is more than sufficient to keep the cockpit
: warm enough for no coat or gloves at -30 degC OAT once I'm flying (I
: have to turn it down quite a bit), but then, in the winter I'm always
: wearing an extra layer of socks and thermal underwear just in case.
: One of my favourite ways to fly in the winter is to open the overhead
: vent a bit *and* pump the heater up to full, but that's probably just
: strange.

My Cherokee probably has the potential of keeping things warm, but
the air leaks elsewhere make it chilly. Seems like while your shoulders,
neck, and arms are freezing from a draft, you simultaneously smell burning
rubber from down by the rudder pedals....

-Cory

--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

Probably poetic license about the "blizzard" part?.
I wish you'd merely said "heavy snow".
Blizzards really are major storms, with winds alone that'll keep me on =
the ground.
---JRC---

"Roger Halstead" wrote in message =
...
=20
=20
=20
=20
=20
Unlike the summer storms, you can fly over a blizzard at some where
between 3000 and 5000 AGL. The winter storms seldom get very high.
=20
.
=20

writes:

My Cherokee probably has the potential of keeping things warm, but
the air leaks elsewhere make it chilly. Seems like while your shoulders,
neck, and arms are freezing from a draft, you simultaneously smell burning
rubber from down by the rudder pedals....

I *feel* the burning down in my feet, even through boots and two pair
of socks -- that's why I eventually have to turn the heat down.


All the best,


David

WIth my Six, I've found that opening the floor vent about half way and turning
the cup to the front avoids the hot foot while at the same time keeping from
freezing out the back seat passengers. Perhaps that would work in the smaller
CHerokees as well?

David Megginson wrote:

writes:

My Cherokee probably has the potential of keeping things warm, but
the air leaks elsewhere make it chilly. Seems like while your shoulders,
neck, and arms are freezing from a draft, you simultaneously smell burning
rubber from down by the rudder pedals....

I *feel* the burning down in my feet, even through boots and two pair
of socks -- that's why I eventually have to turn the heat down.

All the best,

David

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

Ray Andraka writes:

WIth my Six, I've found that opening the floor vent about half way
and turning the cup to the front avoids the hot foot while at the
same time keeping from freezing out the back seat passengers.
Perhaps that would work in the smaller CHerokees as well?

It sounds like a good idea -- I'll give it a try.


Thanks,


David

The pigs will be flying long before there is a 5F day at OAK.

Mike
MU-2


"Fred E. Pate" wrote in message
...
John Bell wrote:
Let me add two links to the discussion:

This is on problems with cold weather altimetry:

http://www.aircraftbuyer.com/learn/train06.htm

This is about the accuracy of unaided GPS altitude in the context of
vertical guidance, but it bears some relavence to the discussion of the
accuracy of GPS altitude:

http://www.bluecoat.org/reports/Graham_2001_RawGPS.pdf

John Bell
www.cockpitgps.com


This one's for the Canadians on this thread. A notice on the new
Oakland, California (KOAK) "RNAV (GPS) RWY 29" approach
(http://www.myairplane.com/databases/.../OAK_agr29.pdf):

"BARO-VNAV NA below -15 deg C (5 deg F)"

And this is for a decision altitude of only 294 ft AGL. Seems like the
FAA is moving towards taking into account temperature errors in
barometric alitmetry. And, by implication, this supports the premise
that WAAS altitude figures are more accurate than the trusty old
"sensitive altimeter." (In the legend they specifically state that
WAAS-based VNAV can be used when BARO-VNAV is not approved due to
temperature.)

Sure, but that's not tne point. These restrictions will be standard on all of these types of approaches nation wide. Its the first time I am aware of that the FAA has included temperature altimetry errors in instrument procedures.

Mike Rapoport wrote:


The pigs will be flying long before there is a 5F day at OAK.

Mike
MU-2


"Fred E. Pate" wrote in message
...
John Bell wrote:
Let me add two links to the discussion:

This is on problems with cold weather altimetry:

http://www.aircraftbuyer.com/learn/train06.htm

This is about the accuracy of unaided GPS altitude in the context of
vertical guidance, but it bears some relavence to the discussion of the
accuracy of GPS altitude:

http://www.bluecoat.org/reports/Graham_2001_RawGPS.pdf

John Bell
www.cockpitgps.com


This one's for the Canadians on this thread. A notice on the new
Oakland, California (KOAK) "RNAV (GPS) RWY 29" approach
(http://www.myairplane.com/databases/.../OAK_agr29.pdf):

"BARO-VNAV NA below -15 deg C (5 deg F)"

And this is for a decision altitude of only 294 ft AGL. Seems like the
FAA is moving towards taking into account temperature errors in
barometric alitmetry. And, by implication, this supports the premise
that WAAS altitude figures are more accurate than the trusty old
"sensitive altimeter." (In the legend they specifically state that
WAAS-based VNAV can be used when BARO-VNAV is not approved due to
temperature.)

I agree in principle but in actuality it never gets cold enough in the US to
make a difference. The only times that we have really low temperatures (-40
and below) there is an inversion.

Mike
MU-2


wrote in message ...
Sure, but that's not tne point. These restrictions will be standard on
all of these types of approaches nation wide. Its the first time I am aware
of that the FAA has included temperature altimetry errors in instrument
procedures.

Mike Rapoport wrote:


The pigs will be flying long before there is a 5F day at OAK.

Mike
MU-2


"Fred E. Pate" wrote in message
...
John Bell wrote:
Let me add two links to the discussion:

This is on problems with cold weather altimetry:

http://www.aircraftbuyer.com/learn/train06.htm

This is about the accuracy of unaided GPS altitude in the context of
vertical guidance, but it bears some relavence to the discussion of
the
accuracy of GPS altitude:

http://www.bluecoat.org/reports/Graham_2001_RawGPS.pdf

John Bell
www.cockpitgps.com


This one's for the Canadians on this thread. A notice on the new
Oakland, California (KOAK) "RNAV (GPS) RWY 29" approach
(http://www.myairplane.com/databases/.../OAK_agr29.pdf):

"BARO-VNAV NA below -15 deg C (5 deg F)"

And this is for a decision altitude of only 294 ft AGL. Seems like the
FAA is moving towards taking into account temperature errors in
barometric alitmetry. And, by implication, this supports the premise
that WAAS altitude figures are more accurate than the trusty old
"sensitive altimeter." (In the legend they specifically state that
WAAS-based VNAV can be used when BARO-VNAV is not approved due to
temperature.)