Tracking around VOR issues - iFly General Discussions

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Tracking around VOR issues

4/7/2011 9:00 PM

ElvisFlyer

Joined: 6/16/2010

Posts: 4

Tracking around VOR issues

I've started instrument training and am using my ifly for situational awareness.

On the two occasions that I've been working on holds, the airplane is defintiley NOT in the right place relative to the nav aid, in this case, a VOR.

For example, the to/from flag flips on my cdi, and my instructor is looking down and there is the vor station, but the ifly indicates I am some distance from it, perhaps a mile or two. Shouldn't it be more accurate than that?

4/8/2011 9:33 AM

Walter

Joined: 7/8/2009

Posts: 2778

Re: Tracking around VOR issues

ElvisFlyer,

The sectional charts were originally (and still are) created for visual navigation. The FAA basically hand-draws these charts, and they are often times less than perfectly accurate. You can test this yourself: Look up the lat/lon for your VOR, then get a ruler and carefully plot the location on your paper chart based on the lat/lon grid printed on the map. You will find that the VOR is actually printed in the wrong location!

But a 2 mile difference is a bit unusual....even one mile is on the outside of the deviations I've noted. But i've not really looked into VORs much, this usually comes up with airports. 1/2 mile is fairly common. What is the VOR? I'd like to look at that one myself.

Thanks,
Walter

Walter Boyd
President, Adventure Pilot

4/8/2011 7:33 PM

ElvisFlyer

Joined: 6/16/2010

Posts: 4

Re: Tracking around VOR issues

Hi Walter,

Thanks for the prompt reply.

It is the Keene, NH VOR

By the way, I really like the Ifly. Keep up the good work. I spoke with Shane quite a bit at Sun n Fun; sounds like you have some great upgrades coming out.

I lived in Collin county for a long time. Went to HS in Plano, back when Plano was nothing, in the 70's. Literally, one stop light betwenn Coit Rd and I-75, and at I-75 it was and 8 way stop sign intersection. McKinney consisted of a town hall with a bunch of old guys playin dominoes on the benches outside, chewin and spittn. I think I remember a general store there, and some kind of diner. My how things have changed.

Joseph

4/11/2011 10:15 AM

Walter

Joined: 7/8/2009

Posts: 2778

Re: Tracking around VOR issues

I measured: That VOR is placed on the sectional chart 0.8 nm too far to the north. This is within typical variance for any of the symbols on a sectional. The FAA seems to be more accurate on the Terminal charts, and the Low-enroutes are almost always spot on.

Those old guys are still plain, chewin, and spittn around here. Our offices are in the historic Cotton Mill in McKinney - a hundred year old factory. We're actually in the old payroll offices. Someone found a half-penny the other day ;-).

-Walter

Walter Boyd
President, Adventure Pilot