Why The Hell... (random rant)

Kev wrote:
On Apr 4, 2:32 am, Tauno Voipio wrote:

EridanMan wrote:

Why in gods name are VOR's Mag heading based?

It's a nuisance for maintenance, but it frees
the pilot from calculating the variation at
the operative time. Just to off-load the pilot.


A good answer. Same for winds in flight, etc. Everything is based on
the magnetic to make it easier for the pilot. At least, the pilot of
old. If we had 100% reliable aids in the plane, then I suppose you
could argue for just following the red line on the electronic map, and
never even know what course you're taking ;-)


I know, ideally, that means that you can sync your DG and your VOR
indicator to fly to a waypoint... except that most VOR's around here
have long since fallen behind Magnetic drift... so - now, not only do
you have to flightplan in True Heading, convert to Mag Heading to get
your vectors, THEN you have to get the corrective factor for each of
the VOR's your using for navigation and note that as well? huh?

If they are off the mag variation, it is
mis-maintenance, and the VOR should be
marked defective or taken off-line.


VORs are allowed to get +/- 6 degrees off. Seems a lot, but it's
only a handful of miles off-course over most VORs' ranges. Anyway,
see:

http://www.naco.faa.gov/index.asp?xml=naco/faq#q2h

Kev


This seems too much to match the ICAO specified system accuracy
of +/- 5.2 degrees. The system accuracy includes transmitter
and receiver errors and the operative margin.

The VORs here are adjusted for an error of less than 1 degree
at the station, and a flight test is not passed if the error
exceeds 3 degrees (except on special terrain cases, which have
to be announced by NOTAMs).

--

Tauno Voipio
tauno voipio (at) iki fi

"Tauno Voipio" wrote in message
...

It's a nuisance for maintenance, but it frees
the pilot from calculating the variation at
the operative time. Just to off-load the pilot.


That would be true if VORs were set to local magnetic variation. They
rarely are.



If they are off the mag variation, it is
mis-maintenance, and the VOR should be
marked defective or taken off-line.


That doesn't happen until they differ by 6 degrees with local variation.

Steven P. McNicoll writes:

That would be true if VORs were set to local magnetic variation. They
rarely are.

Which variation are they set to, and how useful can they be if their
orientation doesn't match the local magnetic variation?

That doesn't happen until they differ by 6 degrees with local variation.

Where did you get this figure?

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

Mxsmanic wrote:
Steven P. McNicoll writes:

That would be true if VORs were set to local magnetic variation. They
rarely are.

Which variation are they set to, and how useful can they be if their
orientation doesn't match the local magnetic variation?

Because some were never right. Some where set right but the local
variation has changed and the VOR's were never realigned. It's
not necessary for them to set exact, just that they are known with
a reasonable precision. The fact that they are close to magnetic
north is again as we've been saying, convenience because all courses
and headings IN FLIGHT are done magnetic.

"Ron Natalie" wrote in message
m...

Because some were never right. Some where set right but the local
variation has changed and the VOR's were never realigned. It's
not necessary for them to set exact, just that they are known with
a reasonable precision. The fact that they are close to magnetic
north is again as we've been saying, convenience because all courses
and headings IN FLIGHT are done magnetic.


If they were set to true north they would still be known with a reasonable
precision. They'd be no less useful and they wouldn't have to ever be reset
due to magnetic drift.

EridanMan wrote:
Are VOR's all MH based?

So that they line up with the compass. All in-flight
navigation is magnetic based.

"Ron Natalie" wrote in message
m...

So that they line up with the compass. All in-flight
navigation is magnetic based.


But VOR radials rarely line up with the compass. Most haven't been adjusted
for changes in local magnetic variation in decades.

Ron Natalie writes:

So that they line up with the compass. All in-flight
navigation is magnetic based.

Some transoceanic flights might disagree.

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

On Apr 4, 7:55 pm, Mxsmanic wrote:
Ron Natalie writes:
So that they line up with the compass. All in-flight
navigation is magnetic based.

Some transoceanic flights might disagree.


No they wouldn't fjukktyard: We use true only when necessary.

Bertie

"EridanMan" wrote in message
oups.com...

Why in gods name are VOR's Mag heading based?


Tradition.