Posted for Walter Atkinson <walter@advancedpilot.com>:

 Yes.  I know Ed Williams.  He created that formula for a few of us a few
years back and I've been using it since.  Ed is a physicist at the Livermoore
Labs and blows up tiny suns for a living while trying to find a better way to
produce energy for us all.  He's a fascinating fellow and a very skilled CFI.
 
 I placed his formula into a spreadsheet so all I have to do is input the
three airspeeds and it gives me the TAS. It is a very reliable method as long
as the wind speed is below the TAS of the airplane!  If that's not the case,
then maybe you oughta not fly that day anyway! <g>
 
 Walter
 
 
"""
 I came across this method from http://williams.best.vwh.net/avform.txt and I
believe it would be usable for Calibration of airspeed indicators if you have
a good GPS:
  
 
 TAS and windspeed from three (GPS) groundspeeds.
...snip...
"""