Compass swinging?

[Roy Smith]

I've got AC 43.13-1B, which describes the procedure to swing a compass.
What I can't find is the bureaucratic stuff -- who can do it (any pilot?),
and what paperwork follow-up is required (airframe logbook entry, or is
just making the new compass card sufficient?).

[Mike Noel]

This is probably something best left to someone with experience to avoid the
frustration of making interacting adjustments until you get it right. I had
the avionics tech do it for me at my last annual. He used test tools to
generate a magnetic field instead of actually taking the plane out onto a
compass rose on the ramp. The guy did a superb job.

--
Best Regards,
Mike

http://photoshow.comcast.net/mikenoel

"Roy Smith" > wrote in message
...
> I've got AC 43.13-1B, which describes the procedure to swing a compass.
> What I can't find is the bureaucratic stuff -- who can do it (any pilot?),
> and what paperwork follow-up is required (airframe logbook entry, or is
> just making the new compass card sufficient?).

[Newps]

Roy Smith wrote:
> I've got AC 43.13-1B, which describes the procedure to swing a compass.
> What I can't find is the bureaucratic stuff -- who can do it (any pilot?),
> and what paperwork follow-up is required (airframe logbook entry, or is
> just making the new compass card sufficient?).

I swung my own several years ago and made a new card. An A&P has to
sign it off.

[zatatime]

On Fri, 24 Nov 2006 22:46:44 -0700, Newps >
wrote:

>
>
>Roy Smith wrote:
>> I've got AC 43.13-1B, which describes the procedure to swing a compass.
>> What I can't find is the bureaucratic stuff -- who can do it (any pilot?),
>> and what paperwork follow-up is required (airframe logbook entry, or is
>> just making the new compass card sufficient?).
>
>I swung my own several years ago and made a new card. An A&P has to
>sign it off.


I also swung my own (and a few friends). Our radio guy did the sign
off. Not to split hairs, but only an airframe license is required for
this one as far as I know. (He says putting on his flame proof
blazer).

HTH.
z

[Bob Noel]

In article >,
Roy Smith > wrote:

> I've got AC 43.13-1B, which describes the procedure to swing a compass.
> What I can't find is the bureaucratic stuff -- who can do it (any pilot?),
> and what paperwork follow-up is required (airframe logbook entry, or is
> just making the new compass card sufficient?).

If it isn't listed as one of the tasks us pilots can do, then you need the A&P
sign-off.

--
Bob Noel
Looking for a sig the
lawyers will hate

[Jay Somerset]

On Fri, 24 Nov 2006 22:00:24 -0700, "Mike Noel" >
wrote:

> This is probably something best left to someone with experience to avoid the
> frustration of making interacting adjustments until you get it right. I had
> the avionics tech do it for me at my last annual. He used test tools to
> generate a magnetic field instead of actually taking the plane out onto a
> compass rose on the ramp. The guy did a superb job.


I have never heard of that method being used, but in principle, I don't like
it! It is always best to calibrate something under the same conditions in
which it will be used. Simulating the earth's magnetic field is just adding
one more approximation to the calibration.

First: Just how did your avionics tech align the generated field with the
airplanes longitudinal axis? How accurately? How could you tell?

Second: How did the tech adjust the generated field to be the same strength
as the earth's magnetic field? It would have to be, or the compass
ajustments will not be correct.

Third: How did your tech eliminate the earth's magnetic field from
influencing the compass during the swinging? Seems your compass was
compensated in the presence of two magnetic fields -- one of which won't be
there when you are flying.

I'm more than a little suspicious about the technique.

[Mike Noel]

Can't give a helpful answer. I just know how he told me he did it and that
the results were excellent.

--
Best Regards,
Mike

http://photoshow.comcast.net/mikenoel

"Jay Somerset >" > wrote in message
...
> On Fri, 24 Nov 2006 22:00:24 -0700, "Mike Noel" >
> wrote:
>
>> This is probably something best left to someone with experience to avoid
>> the
>> frustration of making interacting adjustments until you get it right. I
>> had
>> the avionics tech do it for me at my last annual. He used test tools to
>> generate a magnetic field instead of actually taking the plane out onto a
>> compass rose on the ramp. The guy did a superb job.
>
>
> I have never heard of that method being used, but in principle, I don't
> like
> it! It is always best to calibrate something under the same conditions in
> which it will be used. Simulating the earth's magnetic field is just
> adding
> one more approximation to the calibration.
>
> First: Just how did your avionics tech align the generated field with the
> airplanes longitudinal axis? How accurately? How could you tell?
>
> Second: How did the tech adjust the generated field to be the same
> strength
> as the earth's magnetic field? It would have to be, or the compass
> ajustments will not be correct.
>
> Third: How did your tech eliminate the earth's magnetic field from
> influencing the compass during the swinging? Seems your compass was
> compensated in the presence of two magnetic fields -- one of which won't
> be
> there when you are flying.
>
> I'm more than a little suspicious about the technique.

[Mike Noel]

ps Check out:

http://www.firstmarkaerospace.com/standbycompass.asp

--
Best Regards,
Mike

http://photoshow.comcast.net/mikenoel

"Mike Noel" > wrote in message
. ..
> This is probably something best left to someone with experience to avoid
> the frustration of making interacting adjustments until you get it right.
> I had the avionics tech do it for me at my last annual. He used test
> tools to generate a magnetic field instead of actually taking the plane
> out onto a compass rose on the ramp. The guy did a superb job.
>
> --
> Best Regards,
> Mike
>
> http://photoshow.comcast.net/mikenoel
>
> "Roy Smith" > wrote in message
> ...
>> I've got AC 43.13-1B, which describes the procedure to swing a compass.
>> What I can't find is the bureaucratic stuff -- who can do it (any
>> pilot?),
>> and what paperwork follow-up is required (airframe logbook entry, or is
>> just making the new compass card sufficient?).
>
>

[RST Engineering]

C'mon Roy, you've been around airplanes long enough to know the real
answer -- "Why that compass card has been in the airplane since I bought
it."

Now, if the FAA really wanted to get snotty, they'd go to Part 43, appendix
A, section (b)(4)(i) and ask to see the major repair signoff for the
"calibration of ... instruments", which is what a compass swing is.

Jim




"Roy Smith" > wrote in message
...
> I've got AC 43.13-1B, which describes the procedure to swing a compass.
> What I can't find is the bureaucratic stuff -- who can do it (any pilot?),
> and what paperwork follow-up is required (airframe logbook entry, or is
> just making the new compass card sufficient?).

[Matt Barrow]

"Mike Noel" > wrote in message
. ..
> ps Check out:
>
> http://www.firstmarkaerospace.com/standbycompass.asp
>

Also, this thing is much less prone to errors:
http://www.aircraftspruce.com/catalog/inpages/vertcard_compass.php
and http://www.pai700.com/index.html

[Stan Prevost]

"Matt Barrow" > wrote in message
...
>
>> Also, this thing is much less prone to errors:
> http://www.aircraftspruce.com/catalog/inpages/vertcard_compass.php
> and http://www.pai700.com/index.html
>

Less prone to what kind of errors?

[Matt Barrow]

"Stan Prevost" > wrote in message
...
>
> "Matt Barrow" > wrote in message
> ...
>>
>>> Also, this thing is much less prone to errors:
>> http://www.aircraftspruce.com/catalog/inpages/vertcard_compass.php
>> and http://www.pai700.com/index.html
>>
>
> Less prone to what kind of errors?
Turning, acceleration, deceleration...

[Stan Prevost]

"Matt Barrow" > wrote in message
...
>
> "Stan Prevost" > wrote in message
> ...
>>
>> "Matt Barrow" > wrote in message
>> ...
>>>
>>>> Also, this thing is much less prone to errors:
>>> http://www.aircraftspruce.com/catalog/inpages/vertcard_compass.php
>>> and http://www.pai700.com/index.html
>>>
>>
>> Less prone to what kind of errors?

> Turning, acceleration, deceleration...
>


The ones I have flown with, and installed in my airplane, have those same
errors as the whiskey compass, because they work on the same principle, they
are just geared to indicate direction with a vertical card. They do seem to
be more stable in turbulence. Well, actually I haven't tested acceleration
and deceleration, but turning errors seem to be the same.

The main advantage I find in a vertical card compass is the more natural
presentation they give, it doesn't seem backward like the whiskey compass,
and matches the presenation on other directional instruments.

[M[_1_]]

RST Engineering wrote:
> C'mon Roy, you've been around airplanes long enough to know the real
> answer -- "Why that compass card has been in the airplane since I bought
> it."
>

Same reaction here. Doesn't everyone here have at least two GPS's
onboard that show a ground track bearing 10 times better than the
compass? No lecture about the difference between heading and ground
track please. We're all adults here.

In real life, ATC just wants you to fly from point A to point B in a
straight line. If you're being vectored in anything slower than 250
knots, ATC can't care less if you're flying a 180 degree track bearing
instead of holding a wobbling 185 heading in a 15 knots bumpy
crosswind. They eyeball your radar track after drinking half cup of
coffee, and turn you 10 degrees if need to.

[Roger[_4_]]

On Sat, 25 Nov 2006 16:14:36 -0700, "Matt Barrow"
> wrote:

>
>"Mike Noel" > wrote in message
. ..
>> ps Check out:
>>
>> http://www.firstmarkaerospace.com/standbycompass.asp
>>
>
>Also, this thing is much less prone to errors:
>http://www.aircraftspruce.com/catalog/inpages/vertcard_compass.php
> and http://www.pai700.com/index.html

I've had a vertical card compass for years. The Deb had one in it when
I go it so I'd hardly call it a new, let alone "totally new" concept.
Like a whisky compass it does not give the proper heading at all
times. You still have the lead and lag in turns and it won't set
still in turbulence, but it has far less movement than the whisky
compass in turbulence.

Swinging one is about the same. Just don't use runway headings unless
you know they are right. Ours are about 6 degrees plus so 360 is
really 006 and 060 is really 066. Hence the compass rose at some
airports and that set of tools in the instrument shop.




>
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

[Roger[_4_]]

On Sat, 25 Nov 2006 20:14:12 -0700, "Matt Barrow"
> wrote:

>
>"Stan Prevost" > wrote in message
...
>>
>> "Matt Barrow" > wrote in message
>> ...
>>>
>>>> Also, this thing is much less prone to errors:
>>> http://www.aircraftspruce.com/catalog/inpages/vertcard_compass.php
>>> and http://www.pai700.com/index.html
>>>
>>
>> Less prone to what kind of errors?
>Turning, acceleration, deceleration...

I've been flying behind one for a long time and they suffer from the
same errors. You just don't see them tipping like the whisky compass.


>
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

[Bob Noel]

In article . com>,
"M" > wrote:

> > C'mon Roy, you've been around airplanes long enough to know the real
> > answer -- "Why that compass card has been in the airplane since I bought
> > it."
>
> Same reaction here. Doesn't everyone here have at least two GPS's
> onboard that show a ground track bearing 10 times better than the
> compass?

Nope. not even one GPS. not even a handheld.

--
Bob Noel
Looking for a sig the
lawyers will hate

[Matt Barrow]

"Roger" > wrote in message
...
> On Sat, 25 Nov 2006 16:14:36 -0700, "Matt Barrow"
> > wrote:
>
>>
>>"Mike Noel" > wrote in message
. ..
>>> ps Check out:
>>>
>>> http://www.firstmarkaerospace.com/standbycompass.asp
>>>
>>
>>Also, this thing is much less prone to errors:
>>http://www.aircraftspruce.com/catalog/inpages/vertcard_compass.php
>> and http://www.pai700.com/index.html
>
> I've had a vertical card compass for years. The Deb had one in it when
> I go it so I'd hardly call it a new, let alone "totally new" concept.
> Like a whisky compass it does not give the proper heading at all
> times. You still have the lead and lag in turns and it won't set
> still in turbulence, but it has far less movement than the whisky
> compass in turbulence.

I'd say about one-fourth the movement in any case. What surprised me was how
much less overshoot/undershoot there was during turns. I suspect it's from
being mounted in a jeweled gimbal (?) which dampens movement, instead of
floating in water

The only times (I think) that a whiskey compass is any good is on the ground
or in dead still air during 1.0G accell/decell.

How pilots used to navigate with them alone (wait for some cementhead to say
"they used watches and maps, too") is a testament to their skills.

[Matt Barrow]

"Bob Noel" > wrote in message
...
> In article . com>,
> "M" > wrote:
>
>> > C'mon Roy, you've been around airplanes long enough to know the real
>> > answer -- "Why that compass card has been in the airplane since I
>> > bought
>> > it."
>>
>> Same reaction here. Doesn't everyone here have at least two GPS's
>> onboard that show a ground track bearing 10 times better than the
>> compass?
>
> Nope. not even one GPS. not even a handheld.
>

Infidel!!

[Stache]

Roy Smith wrote:
> I've got AC 43.13-1B, which describes the procedure to swing a compass.
> What I can't find is the bureaucratic stuff -- who can do it (any pilot?),
> and what paperwork follow-up is required (airframe logbook entry, or is
> just making the new compass card sufficient?).


Recently the compass rose has come up office conversation and who,
when, how, and what type of compass survey should be accomplished. I
can assure everyone reading this not all airport have a surveyed
compass rose (calibrated). Many airports have compass roses that may
not be accurate due to underground pipes or other metal objects that
will affect the accuracy of the survey.

The FAA has published a document FAA No. 405, Standards for
Aeronautical Surveys and Related Products that explains why and how a
compass rose should be surveyed.

Next who can perform the calibration to your onboard compass installed
in your aircraft? Only a Repair station with the proper ratings with
the proper training, current manuals available, and proper tooling.
This is where it may get sticky for some. FAR 65 Subpart D for
Mechanics does NOT allow Airframe rated mechanic to calibrate
compasses. Only a repair station with the proper rating can perform
this task. FAR 65.81(a) excluded airframe mechanics form performing
maintenance, major repairs to, and major alterations of, propellers,
and any repair to, or alterations of instruments. FAR 1.1 under
maintenance explains calibrations are considered a repair. So this
just leaves repair stations to adjust your compass.

Needless to say a pilot cannot perform this task as it is not
considered preventive maintenance.

AC 43.13-1B does explain how to perform a compass swing and is
acceptable data however the compass rose has to be surveyed to make it
legal. The repair station will make an airframe record entry stated
what data the followed such as AC 43.13-1B, chapter 1, section 3. FAR
23.1327 explain the installed compass has to be accurate and all
compasses are classified as instruments.

Bottom line is the compass rose has to be surveyed (check with your
local airport) and a repair station has to perform the compass swing
and make a airframe record entry.

Stache

[[email protected]]

Stache wrote:
> Roy Smith wrote:
> > I've got AC 43.13-1B, which describes the procedure to swing a compass.
> > What I can't find is the bureaucratic stuff -- who can do it (any pilot?),
> > and what paperwork follow-up is required (airframe logbook entry, or is
> > just making the new compass card sufficient?).
>
>
> Recently the compass rose has come up office conversation and who,
> when, how, and what type of compass survey should be accomplished. I
> can assure everyone reading this not all airport have a surveyed
> compass rose (calibrated). Many airports have compass roses that may
> not be accurate due to underground pipes or other metal objects that
> will affect the accuracy of the survey.
>
> The FAA has published a document FAA No. 405, Standards for
> Aeronautical Surveys and Related Products that explains why and how a
> compass rose should be surveyed.
>
> Next who can perform the calibration to your onboard compass installed
> in your aircraft? Only a Repair station with the proper ratings with
> the proper training, current manuals available, and proper tooling.
> This is where it may get sticky for some. FAR 65 Subpart D for
> Mechanics does NOT allow Airframe rated mechanic to calibrate
> compasses. Only a repair station with the proper rating can perform
> this task. FAR 65.81(a) excluded airframe mechanics form performing
> maintenance, major repairs to, and major alterations of, propellers,
> and any repair to, or alterations of instruments. FAR 1.1 under
> maintenance explains calibrations are considered a repair. So this
> just leaves repair stations to adjust your compass.
>
> Needless to say a pilot cannot perform this task as it is not
> considered preventive maintenance.
>
> AC 43.13-1B does explain how to perform a compass swing and is
> acceptable data however the compass rose has to be surveyed to make it
> legal. The repair station will make an airframe record entry stated
> what data the followed such as AC 43.13-1B, chapter 1, section 3. FAR
> 23.1327 explain the installed compass has to be accurate and all
> compasses are classified as instruments.
>
> Bottom line is the compass rose has to be surveyed (check with your
> local airport) and a repair station has to perform the compass swing
> and make a airframe record entry.
>
> Stache


When we discussed this topic on another web page I posted this question
to the FAA , and here is the answer I got from them.

An A&P mechanic is authorized to approve an aircraft for return to
service after performing a compass swing. Adjustment of the readily
available compensating adjustments of a wet compass are included in
the
procedures described in AC 43.13-1B Chapter 12, Section 3.

While the FAA believes that the calibration and repair of all
instruments should be classified as appliance major repairs, which
an
A&P mechanic is not authorized to approve and return to service (see
14
CFR §65.85(a)), calibration procedures normally require the
instrument
case to be opened, special skill and knowledge, and the use of test
equipment. Calibration does not include those adjustments of
instruments and equipment which are accomplished using readily
accessible simple adjusting means that do not have an appreciable
effect
on the airworthiness of the instrument. Swinging a compass,
adjusting
the compensators to minimize error, and preparation of a compass
correction card is typically considered minor airframe maintenance.


Charles Fellows
Federal Aviation Administration
General Aviation & Avionics Branch, AFS-350
Phone (202) 267-3922
Fax (202) 267-5115

I hope this clearifies the question of who can swing a compass

Tom Downey A&P-IA

[Roy Smith]

In article om>,
wrote:

> Stache wrote:
> > Roy Smith wrote:
> > > I've got AC 43.13-1B, which describes the procedure to swing a compass.
> > > What I can't find is the bureaucratic stuff -- who can do it (any pilot?),
> > > and what paperwork follow-up is required (airframe logbook entry, or is
> > > just making the new compass card sufficient?).
> >
> >
> > Recently the compass rose has come up office conversation and who,
> > when, how, and what type of compass survey should be accomplished. I
> > can assure everyone reading this not all airport have a surveyed
> > compass rose (calibrated). Many airports have compass roses that may
> > not be accurate due to underground pipes or other metal objects that
> > will affect the accuracy of the survey.
> >
> > The FAA has published a document FAA No. 405, Standards for
> > Aeronautical Surveys and Related Products that explains why and how a
> > compass rose should be surveyed.
> >
> > Next who can perform the calibration to your onboard compass installed
> > in your aircraft? Only a Repair station with the proper ratings with
> > the proper training, current manuals available, and proper tooling.
> > This is where it may get sticky for some. FAR 65 Subpart D for
> > Mechanics does NOT allow Airframe rated mechanic to calibrate
> > compasses. Only a repair station with the proper rating can perform
> > this task. FAR 65.81(a) excluded airframe mechanics form performing
> > maintenance, major repairs to, and major alterations of, propellers,
> > and any repair to, or alterations of instruments. FAR 1.1 under
> > maintenance explains calibrations are considered a repair. So this
> > just leaves repair stations to adjust your compass.
> >
> > Needless to say a pilot cannot perform this task as it is not
> > considered preventive maintenance.
> >
> > AC 43.13-1B does explain how to perform a compass swing and is
> > acceptable data however the compass rose has to be surveyed to make it
> > legal. The repair station will make an airframe record entry stated
> > what data the followed such as AC 43.13-1B, chapter 1, section 3. FAR
> > 23.1327 explain the installed compass has to be accurate and all
> > compasses are classified as instruments.
> >
> > Bottom line is the compass rose has to be surveyed (check with your
> > local airport) and a repair station has to perform the compass swing
> > and make a airframe record entry.
> >
> > Stache
>
>
> When we discussed this topic on another web page I posted this question
> to the FAA , and here is the answer I got from them.
>
> An A&P mechanic is authorized to approve an aircraft for return to
> service after performing a compass swing. Adjustment of the readily
> available compensating adjustments of a wet compass are included in
> the
> procedures described in AC 43.13-1B Chapter 12, Section 3.
>
> While the FAA believes that the calibration and repair of all
> instruments should be classified as appliance major repairs, which
> an
> A&P mechanic is not authorized to approve and return to service (see
> 14
> CFR ?65.85(a)), calibration procedures normally require the
> instrument
> case to be opened, special skill and knowledge, and the use of test
> equipment. Calibration does not include those adjustments of
> instruments and equipment which are accomplished using readily
> accessible simple adjusting means that do not have an appreciable
> effect
> on the airworthiness of the instrument. Swinging a compass,
> adjusting
> the compensators to minimize error, and preparation of a compass
> correction card is typically considered minor airframe maintenance.
>
>
> Charles Fellows
> Federal Aviation Administration
> General Aviation & Avionics Branch, AFS-350
> Phone (202) 267-3922
> Fax (202) 267-5115
>
> I hope this clearifies the question of who can swing a compass
>
> Tom Downey A&P-IA

Thanks! That does indeed answer the question.

[[email protected]]

M wrote:
> RST Engineering wrote:
> > C'mon Roy, you've been around airplanes long enough to know the real
> > answer -- "Why that compass card has been in the airplane since I bought
> > it."
> >
>
> Same reaction here. Doesn't everyone here have at least two GPS's
> onboard that show a ground track bearing 10 times better than the
> compass?

No, and you won't either next time your alternator decides to go
south.

Dan

[B A R R Y[_2_]]

wrote:
>
> No, and you won't either next time your alternator decides to go
> south.

Alternator? We don't need no steenkin' alternator!

Both the avaiation GPS on my panel, and the portable hiking unit in my
bag have alkaline power. The hiking unit even has a magnetic compass
and barometric altimeter.

I also have spare alkalines in my bag and flashlights. <G>

[Matt Barrow]

> wrote in message
ps.com...
>
> M wrote:
>> RST Engineering wrote:
>> > C'mon Roy, you've been around airplanes long enough to know the real
>> > answer -- "Why that compass card has been in the airplane since I
>> > bought
>> > it."
>> >
>>
>> Same reaction here. Doesn't everyone here have at least two GPS's
>> onboard that show a ground track bearing 10 times better than the
>> compass?
>
> No, and you won't either next time your alternator decides to go
> south.
>
Gee, Dan! Do you sleep in a house? You know, you'd be squashed like a bug
when your roof collapses!


--
Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO (MTJ)

[[email protected]]

Matt Barrow wrote:
> > wrote in message
> ps.com...
> >
> > M wrote:
> >> RST Engineering wrote:
> >> > C'mon Roy, you've been around airplanes long enough to know the real
> >> > answer -- "Why that compass card has been in the airplane since I
> >> > bought
> >> > it."
> >> >
> >>
> >> Same reaction here. Doesn't everyone here have at least two GPS's
> >> onboard that show a ground track bearing 10 times better than the
> >> compass?
> >
> > No, and you won't either next time your alternator decides to go
> > south.
> >
> Gee, Dan! Do you sleep in a house? You know, you'd be squashed like a bug
> when your roof collapses!


Don't be dumb. The magnetic compass is legally required because it
operates independently of any electrical supply, unlike any other
navigational doodad you might have. And in some areas we fly here in
Canada, the mag compass has saved a lot of lives when the rest of the
goodies failed. An accurate compass and a pilot able to use it is
absolutely necessary for finding the way home when other stuff quits,
especially the GPS. There are no other navaids in much of this country.
When the visiblility is low, you can miss your airport by a mile or two
and never see it. A one-degree error on a 60-mile track is a mile off
course, so we teach some of our navigation exercises in an airplane
with nothing more than a compass. We have had alternator failures
several times over the years, even with carrying out the 500-hour
alternator inspections.
On the other hand, the compass is mostly useless in the far
North due to magnetic dip. Up there pilots sometimes keep the "sun's
true bearing" tables aboard.

Dan

[[email protected]]

wrote:
: Don't be dumb. The magnetic compass is legally required because it
: operates independently of any electrical supply, unlike any other
: navigational doodad you might have. And in some areas we fly here in
: Canada, the mag compass has saved a lot of lives when the rest of the
: goodies failed. An accurate compass and a pilot able to use it is
: absolutely necessary for finding the way home when other stuff quits,
: especially the GPS. There are no other navaids in much of this country.
: When the visiblility is low, you can miss your airport by a mile or two
: and never see it. A one-degree error on a 60-mile track is a mile off
: course, so we teach some of our navigation exercises in an airplane
: with nothing more than a compass. We have had alternator failures
: several times over the years, even with carrying out the 500-hour
: alternator inspections.
: On the other hand, the compass is mostly useless in the far
: North due to magnetic dip. Up there pilots sometimes keep the "sun's
: true bearing" tables aboard.

: Dan

Pretty telling a year or so ago flying along the Alaska Highway in the Yukon. A 60 mile long Victor airway between two VORs
might have as much as a 5 degree difference from end-to-end headings and "180-degreee reciprocal" headings. In the far Canadian
north, I know it's even worse.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Roger[_4_]]

On Mon, 18 Dec 2006 11:48:14 -0500, B A R R Y >
wrote:

wrote:
>>
>> No, and you won't either next time your alternator decides to go
>> south.
>
>Alternator? We don't need no steenkin' alternator!
>
>Both the avaiation GPS on my panel, and the portable hiking unit in my
>bag have alkaline power. The hiking unit even has a magnetic compass
>and barometric altimeter.
>
>I also have spare alkalines in my bag and flashlights. <G>

And when the GPS signal goes out? It's happened twice. OTOH we're
near the bottom of the solar cycle. BUT OT OH there was a major class
9 coronal mass ejection a week or so ago which fortunately missed us.


Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

[Matt Barrow]

> wrote in message
oups.com...
>
> Matt Barrow wrote:
>> > wrote in message
>> ps.com...
>> >
>> > M wrote:
>> >> RST Engineering wrote:
>> >> > C'mon Roy, you've been around airplanes long enough to know the real
>> >> > answer -- "Why that compass card has been in the airplane since I
>> >> > bought
>> >> > it."
>> >> >
>> >>
>> >> Same reaction here. Doesn't everyone here have at least two GPS's
>> >> onboard that show a ground track bearing 10 times better than the
>> >> compass?
>> >
>> > No, and you won't either next time your alternator decides to go
>> > south.
>> >
>> Gee, Dan! Do you sleep in a house? You know, you'd be squashed like a bug
>> when your roof collapses!
>
>
> Don't be dumb.

Well bless my stars (as my grandfather used to say), that's a great CYA!

>The magnetic compass is legally required because it
> operates independently of any electrical supply, unlike any other
> navigational doodad you might have.

Duh!

>And in some areas we fly here in
> Canada, the mag compass has saved a lot of lives when the rest of the
> goodies failed.

And how many died because they navigated by compass alone and got hopelessly
lost or ran into something...like a mountain?

[[email protected]]

Matt Barrow wrote:
> > wrote in message
> And how many died because they navigated by compass alone and got hopelessly
> lost or ran into something...like a mountain?

People who run into mountains aren't using their eyes, much less
the compass. That's what VFR minima are for. Anyone in the mountains in
low viz is likely to die and it's not the compass' (or the
government's) fault. IFR minima require a flight altitude 2000' above
the peaks.
As I said before: Your fancy electronics (and gyros, too) can
die from any number of diseases, leaving you with only your magnetic
compass, and if it isn't accurate (and you don't have your VNC handy
and know exactly where you are) you might regret it. At least the mag
compass will continue to work much more reliably than the electronics.
ELTs are another item often ignored, and we've heard the stories
of the guys down in the bush, watching the search planes fly over
looking for that needle in the haystack while they think about their
ELT with the long-expired battery. They've just bought the farm for the
price of an ELT battery and recertification. The diaries they leave
behind are sad.

Dan

[Newps]

wrote:
IFR minima require a flight altitude 2000' above
> the peaks.

Above the terrain, not necessarily the peaks. You may be in a valley
several thousand feet below the peaks at a legal IFR altitude.



> At least the mag
> compass will continue to work much more reliably than the electronics.

Work, yes. Relaiably, maybe. Many areas the compass isn't worth a damn.



> ELTs are another item often ignored, and we've heard the stories
> of the guys down in the bush, watching the search planes fly over
> looking for that needle in the haystack while they think about their
> ELT with the long-expired battery.


If you were smart you'd have a second ELT, preferably one you can talk
on, with all those expired batteries that were never used. Carry it
around with you after you crash.

[[email protected]]

Newps wrote:
> wrote:
> IFR minima require a flight altitude 2000' above
> > the peaks.
>
> Above the terrain, not necessarily the peaks. You may be in a valley
> several thousand feet below the peaks at a legal IFR altitude.

Yup. Canadian IFR reg 602.124 (2) says:

(2) When an aircraft referred to in subsection (1) is not being
operated on an airway or air route or within airspace in respect of
which a minimum altitude referred to in paragraph (1)(b) has been
established, the pilot-in-command shall ensure that the aircraft is
operated at or above

(a) an altitude of 1,000 feet above the highest obstacle located within
a horizontal distance of five nautical miles from the estimated
position of the aircraft in flight;

(b) in a region designated as a mountainous region in the Designated
Airspace Handbook and identified therein as area 1 or 5, an altitude of
2,000 feet above the highest obstacle within a horizontal distance of
five nautical miles from the estimated position of the aircraft in
flight; and

(c) in a region designated as a mountainous region in the Designated
Airspace Handbook and identified therein as area 2, 3 or 4, an altitude
of 1,500 feet above the highest obstacle within a horizontal distance
of five nautical miles from the estimated position of the aircraft in
flight.

Nobody (sane) is going to take off with the intention to
navigate that way with just a magnetic compass, because other regs
require sufficient and appropriate radio gear to track such a course
clear of the granite. However, if all the electrical goodies failed, a
mag compass is better than nothing in such a place. But not much
better.
Here in the Rockies the peaks are many and close enough
together that to be legal a pilot isn't going to be IFR in the valleys.
Not legally, anyway. A few try it but usually come to grief. And their
ELTs don't often work, either. Even with a good ELT they hit so hard
that everything shatters.

Dan

[Newps]

wrote:
> Newps wrote:
>
wrote:
>> IFR minima require a flight altitude 2000' above
>>
>>>the peaks.
>>
>>Above the terrain, not necessarily the peaks. You may be in a valley
>>several thousand feet below the peaks at a legal IFR altitude.

> Here in the Rockies the peaks are many and close enough
> together that to be legal a pilot isn't going to be IFR in the valleys.
> Not legally, anyway. A few try it but usually come to grief. And their
> ELTs don't often work, either. Even with a good ELT they hit so hard
> that everything shatters.


We are on the edge of the Rockies and have several airways that go
between mountain ranges and have MEA's many thousands of feet below the
peaks.

[Drew Dalgleish]

On Tue, 19 Dec 2006 20:47:50 -0700, Newps > wrote:

>
>
wrote:
>> Newps wrote:
>>
wrote:
>>> IFR minima require a flight altitude 2000' above
>>>
>>>>the peaks.
>>>
>>>Above the terrain, not necessarily the peaks. You may be in a valley
>>>several thousand feet below the peaks at a legal IFR altitude.
>
>> Here in the Rockies the peaks are many and close enough
>> together that to be legal a pilot isn't going to be IFR in the valleys.
>> Not legally, anyway. A few try it but usually come to grief. And their
>> ELTs don't often work, either. Even with a good ELT they hit so hard
>> that everything shatters.
>
>
>We are on the edge of the Rockies and have several airways that go
>between mountain ranges and have MEA's many thousands of feet below the
>peaks.

I guess the FAA trusts avionics a lot more than the Canadian DOT.

[Drew Dalgleish]

On 18 Dec 2006 11:40:07 -0800, wrote:

>
>Matt Barrow wrote:
>> > wrote in message
>> ps.com...
>> >
>> > M wrote:
>> >> RST Engineering wrote:
>> >> > C'mon Roy, you've been around airplanes long enough to know the real
>> >> > answer -- "Why that compass card has been in the airplane since I
>> >> > bought
>> >> > it."
>> >> >
>> >>
>> >> Same reaction here. Doesn't everyone here have at least two GPS's
>> >> onboard that show a ground track bearing 10 times better than the
>> >> compass?
>> >
>> > No, and you won't either next time your alternator decides to go
>> > south.
>> >
>> Gee, Dan! Do you sleep in a house? You know, you'd be squashed like a bug
>> when your roof collapses!
>
>
> Don't be dumb. The magnetic compass is legally required because it
>operates independently of any electrical supply, unlike any other
>navigational doodad you might have. And in some areas we fly here in
>Canada, the mag compass has saved a lot of lives when the rest of the
>goodies failed. An accurate compass and a pilot able to use it is
>absolutely necessary for finding the way home when other stuff quits,
>especially the GPS. There are no other navaids in much of this country.
>When the visiblility is low, you can miss your airport by a mile or two
>and never see it. A one-degree error on a 60-mile track is a mile off
>course, so we teach some of our navigation exercises in an airplane
>with nothing more than a compass. We have had alternator failures
>several times over the years, even with carrying out the 500-hour
>alternator inspections.
> On the other hand, the compass is mostly useless in the far
>North due to magnetic dip. Up there pilots sometimes keep the "sun's
>true bearing" tables aboard.
>
> Dan
>
I've flown all over ontario wit just a map and compass in an old
champ. If you're reading the map the compass doesn't have to be ver y
accurate. In fact unlessyou're spending half your tme playing with
your E6B you can't correct for wind drift within 1 degree so why even
try. I now fly with a portable GPS and I like it a lot. It makes me
very lazy about plotting my course but I still have to know where I am
on the map.