In defense of Mr. William's math... sitting at KORD RW32L... I get an initial bearing of 310 to 3CK.

 

I have used the GC math on that website for many years. It is most definitely not inaccurate at all.

The equation http://williams.best.vwh.net for distance is wrong. It omits the radius of the earth.

 

Distance between points

The great circle distance d between two points with coordinates {lat1,lon1} and {lat2,lon2} is given by:

d=acos(sin(lat1)*sin(lat2)+cos(lat1)*cos(lat2)*cos(lon1-lon2))

Might want to do a bit more reading to grasp why you see no earth radius in the calculation. There's a valid reason, and the calculation is accurate as it is written.

Yes, but that doesn't  account need to convert into decimal degs from degminsec units in the first case.

 

And that was my problem. Many thanks Gerry.