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