On an airplane carrying 100 passengers, how many customers does it take, on average, to cover the cost of the flight?

The Middle Seat asked US Airways and consulting firm Oliver Wyman to crunch airline expenses down to the percentages that an individual passenger pays, taking a hard look at costs of running an airline. US Airways created a hypothetical flight of 100 passengers. Each one paid the average $146 fare for a domestic flight ($292 round-trip), plus $18 each in fees and add-ons, based on a year's worth of data ending...