It’s just not the official way. There is a small issue that you do need to taxi some distance in a straight line to give the gps a chance to figure out the ground track. And then be able to stop and park for a bit while you twiddle the adjustment screws. IMHO this should work okay.
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Do i need a compass?
- Thread starter gassman
- Start date
And when stopped, you need the GPS course to stay steady, but there's no guarantee it will...it depends on the Kalman filter used. The computed GPS position, which is all that GPS "knows" (well, that and time), moves around (everything else is computed from that...velocity, heading, etc.). But without knowing the details of the Kalman filter, you don't know how heading is computed and estimated.
I've wondered about the accuracy of swinging a compass over a maze of rebar
Wrap it with nickel sheet metal. Worked for me. I used to have an old navaid autopilot right underneath my compass. My compass would only swing 270° no matter what. Wrapped the navaid in nickel sheet metal and I had a perfect compass swing.
Edit… you’d actually want to wrap the metal things around the compass, not the compass.
I said, I point the nose at the vor (that I can see). Something else.
Not enough information to know how you compensated for the offset between the aircraft VOR antenna position and the axis of aircraft rotation.
We'd need to know the distance of the aircraft from the VOR, and that offset, to know if it introduces a significant error.
This is a trivia question! Assume you know you’re right on the radial, you made a zero distance turn to point directly at the station. What is still wrong?
rtlongdon
Well Known Member
Two words: VOR and declination.
Heaven only knows the last time that VOR was aligned. It can easily have been 30+ years for many VORs.
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It's maintained by the FAA. Of course it's perfect..........
Ah!
, I was hopeful until you did the edit. 
I think that it is essentially the airframe/cockpit as I really don't have any electrical equipment anywhere near it - everything is steam gauge and the radio is underneath on the floor between the legs .... I wonder if you wrapped the compass with it if it would block the magnetic field to the compass....? idk 
i think swinging a compass is in the same boat as an ndb approach...........not very precise. i would think the variance in a gps signal is nothing compared to the errors involved in swinging a compass. like is the airplane lined up exactly on the heading you want?
RV7A Flyer,
My DAR believed it was a must have item.
I put one in somewhat begrudgingly.
During 1st flight I had a total black-screen incident.
Even then, I did not have to have it as I was familiar with the area and in VFR conditions.
I found it antiquated that the only 2 working instruments in my "new" plane was the wet compass and my watch.
Real old school for a modern glass cockpit.
Daddyman58
in the FD they list the declination which was used to align the the VOR radials.
eg
MARTINSBURG (L) (L) VORTACW 112.1 MRB Chan 58 N39º23.13´ W77º50.90´ 286º 6.3 NM to fld. 600/7W
Compare that to the current declination https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml or on sectional. It is 10° for MRB. so the radials are 3 degrees off. Do mental gymnastics to figure out where you actually point at when looking at the VOR from a known radial. Get it wrong every time
rtlongdon
Well Known Member
My instructor used to call it the built in crosswind. We have a couple near me that are >5 deg off. One was last aligned in 1973.in the FD they list the declination which was used to align the the VOR radials.
eg
MARTINSBURG (L) (L) VORTACW 112.1 MRB Chan 58 N39º23.13´ W77º50.90´ 286º 6.3 NM to fld. 600/7W
Compare that to the current declination https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml or on sectional. It is 10° for MRB. so the radials are 3 degrees off. Do mental gymnastics to figure out where you actually point at when looking at the VOR from a known radial. Get it wrong every time
