John T. and other fellow ppruners,
Did not mean to cause ripples here, after all I thought it was a discussion forum. Anyways heres some supporting documentation and Authoritative References....
Regarding Range and Headwind - refer to Aerodynamics for Naval Aviators by H.H. Hurt Jr. (ISBN 1-56027-140-X) page 170 second para from the top left.
Regarding Vmca and Vmcg: I agree that I could be wrong about Vmca and Vmcg on a B747. I was writing in reference to an airplane performance graph depicting the various speeds in a timeline. In the graph (generic airplane) Vmcg was depicted before Vmca. Vmca, from my basic performance classes, is the threshold speed for getting airborne, so should follow Vmcg, which is the threshold speed for continuation of takeoff. If Ive stated something wrong please let me know why? The rest of the info on Vmca and Vmcg I provided is listed in Aircraft Performance Theory for Pilots by P.J. Swatton 2000 (ISBN 0632-05569-3) pg 138 third para from the top.
Regarding Stall Speed at high altitude: The formula for stall speed is given by Vs (ktas) = Sqrt (295 L/qSClmax) where q is the density ratio. However since the speed is given in Vs (ktas), this part of the formula can be rewritten as Vs(ktas) = (SMOE)*(EAS) where SMOE = 1/sqrt(density ratio). When both equations are simplified the density ratios at altitude cancel out leaving only EAS. Position error also cancel each other. Refer to Classnotes for Basic Aerodynamics by Norbert R. Kluga 1991 page 124 from Embry-Riddle Aeronautical University and Flight Technique Analysis for Professional Pilots by Les Kumpula page 30 also from Embry-Riddle Aeronautical University.
Cheers