I was drinking some not very good Shiraz last night up front - thinking about how much it costs to fly me. I'll do 160,000 miles this year on Co @ 6.5 cents a mile. Discounting the cost of the first class meal and the seat - both of which would have gone to waste without me there and budgeting the wine at $5 a bottle - say $1 worth for my share - the real cost is the additional fuel per mile per pound of me and my bags. I weigh 150lbs and carry not more than a briefcase and a change of clothes - say 10lbs. Let's assume the seat in coach would have flown emtpy if they had not sold me the ticket (a big assumption but it is one they make when the let me by U-tickets way out and presumably that is one thing they have sophisticated statisticans work on). (Let's assume I spend all the miles I earn (300,000) on coach fllights @ 50,000 each rt coast to coast for my family.) Assume I am on a newish 737-800. Based on current oil prices, how much do I cost per mile?

According to CO's recent SEC filings the Mainline CASM (Cost per Available Seat Mile) for the first and second quarter 2006 is around $.1035-$.1072, so you can't say that you ain't gettin' what you paid for.*

* Excluding the "valuable" NonePass� miles.

Yeah, but that is not really responsive - assume I am the lowest fare on the plane and without me the seat would fly empty. What is the MARGINAL cost of flying me and my bags per mile per pound?

This number was posted a while back. Presuming the flight is not overbooked, and they didn't lose revenue or have to bump someone to give you your seat, the cost to fly an incremental person is extremely low (under $25).

btw, at $0.065/mile, you're likely not the lowest fare on the plane.