BEagle: So if two nearby VORs deviate by several degrees (I've seen 3-5 degrees difference at least), then their local variation differs by that much?
Not that I don't believe you, but I find this kind of surprising, since the bracketing isogonic lines should specify the regional variation to 1-degree accuracy. BEagle, do you have any background material or reference on this?
Furthermore, what's the best practice for doing flight planning along Victor airways?
1. Use the magnetic track specified for the airway on the sectional?
2. Measure the magnetic track of the airway with a protractor?