Why are headings still magnetic?

Bob Moore wrote:
Andrew Sarangan wrote
So, I still don't agree that navigation systems have
advanced to the point where we can abandon the
magnetic based instruments.

Hmmmm....I wonder how we used to navigate 'over-the-pole'
back before INS? Hint....Grid Navigation, an unslaved
DG referenced to true north.

I don't claim to know anything about navigation over the poles, but if
it is as simple as you say it is, why do we continue using the
magnetic compass for every-day navigation? My guess is that it must be
complex, difficult, expensive or unreliable.

Andrew Sarangan writes:

So what instrument would you suggest we use for true headings?

A combination of INS and GPS would work. It would be at least as
accurate as a compass.

This could be cross-checked against a magnetic heading internally as
long as the exact location of the geomagnetic poles are known.

An ANS could give you true heading even standing still.

GPS does not give you true heading; it can only give a true course. You can't
reliably use a GPS for verifying your runway heading.

As soon as you move, GPS can give you a heading, and an INS can
maintain it for you.

GPS headings only work when you are in motion. Remember the Comair
accident? I suspect such accidents will increase if we switch to GPS
based true headings.

How you navigate with true headings is irrelevant here; the important
thing is that true headings never change.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Mxsmanic wrote:
Andrew Sarangan writes:

So what instrument would you suggest we use for true headings?

A combination of INS and GPS would work. It would be at least as
accurate as a compass.

Accuracy isn't the problem. Would it be as reliable?
Would it be affordable and workable in airplanes that lack
electrical systems? And would it work when those
electrical systems failed?

If you're talking about high budget commercial aviation, any
nav system that has the processing power to decode the
GPS signals has the power to apply a local magnetic
deviation to its heading or course output. Updates to
the magnetic deviation can be distributed as needed
with the updates to the nav database. So for these
users, it's sort of arbitrary which reference is used,
as long as there is an agreed upon reference.

For the gliders, Piper Cubs, and other moderate budget
flyers, the price and reliability differences between a
compass and an INS weigh significantly in favor of the
compass.

There is the further issue of inertia. Every pilot flying today
learned to use magnetic headings. Every airplane cockpit
has an instrument (or several instruments) to prominently
display the magnetic heading to the pilot. To convert
wholesale would entail a period of minor confusion at
least.

Finally, what problem would it solve? The shifting of
the Earth's magnetic poles is slow, relatively
predictable, and something we have lived with for
awhile. While true headings may be more elegant
and stable over the very long term, that elegance
doesn't add much practical value.

--Rich

wrote in message
oups.com...
Finally, what problem would it solve? The shifting of
the Earth's magnetic poles is slow, relatively
predictable, and something we have lived with for
awhile. While true headings may be more elegant
and stable over the very long term, that elegance
doesn't add much practical value.

It's the typical case of a solution in search of a problem...

Grumman-581,

It's the typical case of a solution in search of a problem...


You got that right.

--
Thomas Borchert (EDDH)

Grumman-581 wrote:
wrote in message
oups.com...
Finally, what problem would it solve? The shifting of
the Earth's magnetic poles is slow, relatively
predictable, and something we have lived with for
awhile. While true headings may be more elegant
and stable over the very long term, that elegance
doesn't add much practical value.

It's the typical case of a solution in search of a problem...

This is like the remark from non-aviators why we still use the archaic
units of nautical miles and knots. I have also had people comment why I
continue to use "clunky old Linux" instead of windows. The latter one
was from a highly educated person in Engineering. Clearly, these
types of remarks are due to misconceptions or lack of knowledge. I am
glad these people don't run the world (or may be they already do:-))

writes:

Accuracy isn't the problem. Would it be as reliable?
Would it be affordable and workable in airplanes that lack
electrical systems? And would it work when those
electrical systems failed?

In modern aircraft, a failure of electrical systems brings a lot more
problems than mere navigation errors. No radio, no other navaids, no
control surfaces in some aircraft, no propulsion in some aircraft.

And while a compass shows magnetic north, that's all it shows. You
have no idea how far north or south you are, or which direction to fly
to your destination.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Mxsmanic,

And while a compass shows magnetic north, that's all it shows. You
have no idea how far north or south you are, or which direction to fly
to your destination.


And having true heading (and only that) changes this problem how?

--
Thomas Borchert (EDDH)

Mxsmanic wrote:
In modern aircraft, a failure of electrical systems brings a lot more
problems than mere navigation errors. No radio, no other navaids, no
control surfaces in some aircraft, no propulsion in some aircraft.

And while a compass shows magnetic north, that's all it shows. You
have no idea how far north or south you are, or which direction to fly
to your destination.

You "fly" a PC flight simulator (game)... Even if the poles do shift,
it's not going to effect your game, so don't worry about it...

You are obviously on the wrong newsgroup... Perhaps you should go to
comp.pc.ibm.pc.games.flight-sim or rec.aviation.simulators and leave
this group for real pilots...

Because that's the way it's always been done?