M

Mike Howard

I'm New Here
I am looking for a compas rose near Omaha Nebraska to calibrate my newly installed Dynon D-100 EFIS. Does any one know were one is located or how to find one?
 
Swinging Compass

Mike,
I don't want to sound like a hack or anything, but.......
We didn't have a rose on our airport but our runway was 9/27!
I got the bright idea that why not create my own compass rose!
I noticed my next door neighbors hangars ramp was hugh....for his PC-12.
and had expansion saw cuts on a grid in his beautiful Concrete slab.
I took my trusty Boy Scout compass and checked the grid in several places and found the saw cuts to be perfectly aligned with the main axis.
You could duplicate this with a chalk line and tape measure.

I figured this was luck and the fact the runways are aligned with the axis and most everything on the airport is either parallel or perpendicular to it.
Seemed to me it was hard to move the plane around and then eyeball the alignment over the axis anyway, its easy to get tired of moving up and back to get it perfect, the tailwheel end is easy, but sighting the nose between the gearlegs was harder.

Also when you swing the compass, each adjustment is a compromise to the error of the opposite axis and the compass itself.....so in todays GPS world of tracks and headings etc, I felt my self created rose was good enough.
Just my 2 cents.
 
alpinelakespilot2000 said:
Check your airport facility directory. I forget the symbol or wording used, but they should be listed there. good luck.
Click to expand...

I think there is a reason for not remembering the symbol. I don't see a listing for a compass rose symbol or contraction in the A/FD legend pages.

So, even though I am resurecting a very old thread, Mr. Howards question still stands...."How does one find airports with a compass rose?"
 
I just used my trusty Boy Scout compass.

Pulled the plane out, turned the prop vertical (make sure your mags are off), then using the compass, lined the plane up with magnetic North, sighting along the VS and the prop. Turn the plane and repeat as needed.
 
N941WR said:
I just used my trusty Boy Scout compass.

Pulled the plane out, turned the prop vertical (make sure your mags are off), then using the compass, lined the plane up with magnetic North, sighting along the VS and the prop. Turn the plane and repeat as needed.
Click to expand...

Thanks Bill, but the Silva is not as accurate as I want. I am looking for something that has been surveyed.
 
Using a gps, find an open ramp area, taxi fast enough for the gps to begin recording ground speed, then taxi to align your gps track on north, then stop. Now you have a north/south reference to begin your calibration procedure.
 
Last edited:
rzbill said:
I think there is a reason for not remembering the symbol. I don't see a listing for a compass rose symbol or contraction in the A/FD legend pages.

So, even though I am resurecting a very old thread, Mr. Howards question still stands...."How does one find airports with a compass rose?"
Click to expand...

A compass rose is maintained at the discretion of the airport operator (or local volunteers). The A/FD does not "list" them but often the airport operator will include information about a compass rose in the remarks section of the A/FD. Beyond that, I think it is just local knowledge about where they are located. I think they are becoming fewer and further between.
 
I'd use Google Earth on airports near you. You should be able to find a compass rose right quick. Or you could call the airport and ask.
 
TomVal said:
Using a gps, find an open ramp area, taxi fast enough for the gps to begin recording ground speed, then taxi to align your gps track on north, then stop. Now you have a north/south reference to begin your calibration procedure.
Click to expand...

I agree.
A simple procedure is detailed in an old RVator HERE
 
Silly me. I read that and thought, "Now, why the heck would Mike be installing a D-100?" I really need to remember to look at the post date. :)
 
rzbill said:
Thanks Bill, but the Silva is not as accurate as I want. I am looking for something that has been surveyed.
Click to expand...
The sad reality is that you won't be able to align the airplane to any compass rose that accurately, in the time it will take before the calibration procedure in the Dynon times out... :)

At least, that's true with the D10A.

I used a compass app in my cell phone to verify that the taxiway in front of my hangar was aligned with my home airport's runway, then used the same app to find North, East, South, West. Aligned the airplane by sighting the vertical stab to the center of the canopy (remember that the engine is offset so aligning to the prop will give you a degree or so of error...).

It's certainly accurate enough for VFR flight...
 
Thanks for the answers.

I am well aware of the work around of hand held compass or GPS usage. Thank you for posting these for others benefit.

I am trying to debug a magnetometer problem and a rose would be much more convenient than the other ways.

At least we have cleared the air regarding the A/FD.
 
Be sure to check actual runway heading!

When referring to runway numbers, remember that runways use only 2 digits rounded off. So the numbers can be off as much as 4 or 5?, and even more if they haven't been recently surveyed.

i.e. The actual heading for runway 17 can be anywhere between 165? and 174?. And that is only if the survey is current.
 
Last edited:
Mel said:
When referring to runway numbers, remember that runways use only 2 digits rounded off. So the numbers can be off as much as 4 or 5?, and even more if they haven't been recently surveyed.

i.e. The actual heading for runway 17 can be anywhere between 165? and 174?. And that is only if the survey is current.
Click to expand...

True on the numbers, but a quick check on Airnav.com will give the magnetic and true headings...

http://www.airnav.com/airport/KRYN
 
Also, another bug in the works... Our EAA chapter is thinking of doing a compass rose as a project. We talked to our airport engineer, and he said to be accurate (and really, setting up an EFIS should be accurate) we had to do more than just determine true direction. Compass variations can be caused by metal buildings, fuel tanks, and (according to him) even re-bar in the concrete. He suggested doing it on asphalt some distance from any structures. I really don't know how much of a problem these things can cause, but it is something to consider.

While runway numbers can be off by 4-5 degrees, you can look up the true direction. That may be helpful, at least in seeing how accurate your compass is.

Bob
 
GPS

I also used the GPS trick (GNS430W). Calibrating the D180 required four cardinal headings. I was fortunate to have a ramp large enough to do it.

I'm betting it was at least, if not more, accurate than a compass rose.

Don
 
videobobk said:
Also, another bug in the works... Our EAA chapter is thinking of doing a compass rose as a project. We talked to our airport engineer, and he said to be accurate (and really, setting up an EFIS should be accurate) we had to do more than just determine true direction. Compass variations can be caused by metal buildings, fuel tanks, and (according to him) even re-bar in the concrete. He suggested doing it on asphalt some distance from any structures. I really don't know how much of a problem these things can cause, but it is something to consider.

While runway numbers can be off by 4-5 degrees, you can look up the true direction. That may be helpful, at least in seeing how accurate your compass is.

Bob
Click to expand...

The FAA talks about over 100 yds. from any metal object, which would include rebar...

http://www.faa-aircraft-certification.com/support-files/ac43_13_1b_sec_3.pdf
 
engine running?

I also used the GPS trick (GNS430W). Calibrating the D180 required four cardinal headings. I was fortunate to have a ramp large enough to do it.

I'm betting it was at least, if not more, accurate than a compass rose.
Click to expand...

As far as I remember the engine is supposed to be running along with everything else in the cockpit that normally is on for compass calibration.

If you use a GPS method you won't have to worry about magnetic variations and interference from metal rebar and buildings.
You do need a fairly large ramp to get some tracking history on your GPS readout.
All together a better and more accurate approach than trying to position yourself on top of a compass rose.
 
Sure do miss reclining in the easy chair after returning (sprinting) from the mail box with my new RVator in hand to comb through. :)
 
I know this thread was started a long time ago but I thought I would chime in. Years ago the 99s used to keep up a lot of the compass roses. They might have something about them on their website if they still do this.
 
You must log in or register to reply here.