Why are headings still magnetic?

Mxsmanic wrote:
Like AM radio, magnetic headings are still with us, even though
navigation in general has advanced by leaps and bounds. When will
true headings be used? The magnetic poles are in continuous motion;
the rotational poles are stable.

Eventually, the magnetic poles will move so far that every station and
aircraft everywhere will have to be recalibrated to account for it,
and all charts will have to be changed. And the poles occasionally
reverse, which would also be somewhat of a disaster for
magnetically-based aviation.

Any Earth-based coordinate system is bound to be out of date soon.
We'll be navigating to the moon and other planets and the concept of
"North" won't be relevant. So, we need to figure how navigation will
work in the Solar system and embed Earth navigation in that system. My
guess is that a system similar to GPS but with stations on the other
planets will work until we venture out of our Solar system.

"RST Engineering" wrote:
There is one, and ONLY one instrument in the aircraft that does not
require a power source or have a common catastrophic failure mode.

You mean the wings or the pilot?

Ducks and runs

"Thomas Borchert" wrote in message
...
Mxsmanic,

Seems like the airports around me have
had the same runway numbers for quite a while,


The direction has to change by up to 10 degrees for a change in
numbering.

--
Thomas Borchert (EDDH)

No, 5 if perfectly aligned to start, 5 in one direction and 5 in the
other if not aligned.

On Sat, 02 Sep 2006 16:14:32 -0400, Stubby
wrote:
Any Earth-based coordinate system is bound to be out of date soon.
We'll be navigating to the moon and other planets and the concept of
"North" won't be relevant. So, we need to figure how navigation will
work in the Solar system and embed Earth navigation in that system. My
guess is that a system similar to GPS but with stations on the other
planets will work until we venture out of our Solar system.

I seem to remember some talk awhile back about each star having it's
own electomagnetic signature and the attempt to base a navigational
system upon this... Awh, 'ell, this is probably classified, so just
forget that I said anything... grin

this-message-will-self-destruct-in-five-seconds

Joe,

No, 5 if perfectly aligned to start, 5 in one direction and 5 in the
other if not aligned.


Let's assume Runway23. It's designated when the real direction is 225.
Now, how much has the real direction to change upwards for it to be
designated 24?

--
Thomas Borchert (EDDH)

On Sat, 02 Sep 2006 21:30:18 -0000, Jim Logajan
wrote:

"RST Engineering" wrote:
There is one, and ONLY one instrument in the aircraft that does not
require a power source or have a common catastrophic failure mode.

You mean the wings or the pilot?

Ducks and runs

What about a compromise?
Calibrate the compass as normal but have the lubber line variable so
you can preset the magnetic variation for the area you fly. That way
you can use true headings based on the compass. Maybe a problem if
your partial panel and are using the compass.

The only snag I see is in areas of very large variation. If the
variation was too large I guess you start getting parallax errors too.

Do the modern solid state compasses have provision to change the
variation? That would make it easy or am I missing something?

Thomas Borchert writes:

Let's assume Runway23. It's designated when the real direction is 225.
Now, how much has the real direction to change upwards for it to be
designated 24?

Eleven degrees.

However, if it is designated 22 (it can be 22 or 23 if the real
heading is 225), an increase of only one degree in its true magnetic
heading would require a change to 23.

The rule is to round the true magnetic heading to the nearest multiple
of ten and then drop the last digit. If the true heading ends in 5,
you can round up or down (there is no preference).

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

Jim Logajan writes:

You mean the wings or the pilot?

Both wings and pilot have some catastrophic failure modes, although
those modes are not typical.

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

Grumman-581 writes:

I seem to remember some talk awhile back about each star having it's
own electomagnetic signature and the attempt to base a navigational
system upon this... Awh, 'ell, this is probably classified, so just
forget that I said anything... grin

The SR-71 navigated by finding stars in the sky and obtaining a fix
from them. I think it needed only three stars in order to do this.
It could do it even in daytime. It wasn't quite as accurate as GPS,
but it was more accurate than anything other than an INS at the time,
and it had better long-term stability.

I think the details of the system may still be classified. I always
wanted to know how it could see stars in daylight (although it could
not see them through cloud cover).

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

DCA (Washington) changed its 00-18 to 01-19 a few years ago.


Mxsmanic wrote:
Thomas Borchert writes:

Let's assume Runway23. It's designated when the real direction is 225.
Now, how much has the real direction to change upwards for it to be
designated 24?

Eleven degrees.

However, if it is designated 22 (it can be 22 or 23 if the real
heading is 225), an increase of only one degree in its true magnetic
heading would require a change to 23.

The rule is to round the true magnetic heading to the nearest multiple
of ten and then drop the last digit. If the true heading ends in 5,
you can round up or down (there is no preference).