"Gary Drescher" wrote in message
news:ir3vc.37599$Ly.13077@attbi_s01...

So isn't that a good argument against using marginal cost as a basis for
determining fair payment?


In subway trains, yes; in aviation, no.



Yet when discussing GA fees, you seem to favor a
marginal-cost assessment:


Of course. That's the fair way to do it. Think about it for a moment.
What portion of the national aviation infrastructure would not exist if GA
did not exist? Whatever it costs to support that portion is GA's fair
share. Now, what portion of the bus or subway system would not exist if
there were no bus or subway riders? All of it, of course!

It's fair for bus or subway riders to all pay the same fare because they all
pose the same cost on the system. It's not fair to charge GA and air
carriers the same fees because GA poses far smaller costs on the system.