The opening post on this thread has the Federal DOT site, which
has the
data the Reason Foundation uses. They use the operating subsidy
per
passenger mile statistic,

Precisely...averages, but I want to read about marginal costs of
GA, or why this approach is not valid. In our Class B area, it's
basically about bizjets, burning like $50/hour in fuel tax. It's
very clear to me that if those guys weren't up there, only one ATC
position -- the "satellite controller" -- goes away. But knowing
gov't from the inside as I do, FAA will find a position for that
guy in some understaffed place. A net loss to the Treasury. User
fees are all about getting additional money that Congress won't
provide through the appropriations process, unless they repeal the
fuel tax. Is that seriously the plan?

Fred F.