Why The Hell... (random rant)

EridanMan wrote:
Are VOR's all MH based?

I was flightplanning the other day (I must be one of the few poor
souls left who flight-plans by hand... I guess I just haven't been
flying long enough to get sick of it yet, I consider my flight
planning to be 'part of the experience') And I got to thinking-

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.

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.

--

Tauno Voipio, avionics engineer, CPL(A)
tauno voipio (at) iki fi

writes:

Where do you get a true north compass?

Aviation uses magnetic compasses less and less, and every other navigation
method works best with true north.

Your comment about magnetic south being unusable is just asinine.

Magnetic south isn't exactly the opposite of magnetic north on the Earth's
surface, so if one entity uses it, all must use it, or make constant
corrections to convert between the two. In fact, the failure of the line
between the poles to pass through the center of the planet introduces
additional complications into precise use of a compass. Not to mention the
many other factors that get in the way.

Early navigators used it because they had nothing better. Today there are
lots of things that are better.

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

writes:

You got a true north compass in your airplane?

Both GPS and inertial navigation platforms can easily determine true north.
In fact, they work with true north, and must apply an unpredictable conversion
factor to true north to get current and local magnetic north.

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

TheSmokingGnu writes:

Nothing about the accuracy of the VOR station itself, though.

1-1-3 (1): Accuracy of better than 1 degree.

--
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Tauno Voipio writes:

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

Be careful what you wish for.

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

EridanMan wrote:
Are VOR's all MH based?

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

Mxsmanic wrote:
EridanMan writes:

I'm sorry... call me lazy, but if your not going to keep them all
updated with Magnetic north, then at least stick them on a standard
baseline... True North, for example?

I think aviation should have started moving towards true north for everything
long ago, but that's just me. The constant shifting of the magnetic poles
(which is accelerating) means perpetual updates for anything that depends on
magnetic north (and you can't use magnetic south, because it isn't even
exactly opposite magnetic north).


Because we don't have a TRUE NORTH indicator in the cockit. Just
a magnetic compass and instruments derived from it. Real flying
ain't a stupid-assed computer simulation.

Mxsmanic wrote:

Magnetic south isn't exactly the opposite of magnetic north on the Earth's
surface,

No you are confused. Magnetic SOUTH is the exact opposite of magentic
north you fool. The fact that the MAGNETIC SOUTH POLE is not exactly
opposite the MAGNETIC NORTH POLE is a different issue. The fact that
the poles aren't aligned with the arbitrary "true" datum just means that
the variation equations aren't as simple as they might be. This is why
we just resort to looking it up on a chart.

Early navigators used it because they had nothing better. Today there are
lots of things that are better.

Really, like what? Compasses are still damned reliable compared to
anything else. Cheap too. The only thing that presumes to do better
perhaps is GPS. And it's easier to program that to deal with the
magnetic measurements than to try to force everybody else the other
way.

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

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


Tradition.

wrote:


If the drift is sufficient ( 2 or 3 degrees, I forget the number; it's
in the AIM ) they are supposed to be recalibrated.

The uncertainty in the wind drift angle is usually a lot more than
that.

Huh? What does the wind have to do with VOR's. If the needle is
centered, you're within the tolerance of the VOR. The tolerance
is primarily 4-6 degrees. This keeps you inside the airway at
moderate distances from the VORs.