Airlines weigh costs, revenue in picking planes

— Airlines have been cutting passenger-carrying capacity by reducing the number of flights and using smaller planes instead of bigger ones on some routes.

The carriers hope that by reducing the supply of seats, they can drive up fares. But it's also a way to reduce costs.

Pilots who fly bigger planes earn more money. The big jets can also run up big maintenance bills, and they burn more jet fuel.

The Airline Data Project at MIT collected the numbers from filings that the airlines make with the U.S. Transportation Department and confirmed that small jetliners are cheaper to operate than big ones.

Here's how much American Airlines spent per block hour on pilot costs and maintenance for three types of aircraft. Block hours count the time from when a plane pushes away from the departing gate until it pulls up to the gate after landing.

— For small, narrow (one center aisle) jetliners with 150 or fewer seats: $657 per hour on pilots, $715 per hour on maintenance, and they burned 940 gallons of fuel per hour.

— For one-aisle jets with at least 151 seats: $746 per hour on pilots, $888 per hour on maintenance, and they burned 1,250 gallons per hour.

— For so-called widebody jets with two aisles in the cabin: $1,043 per hour on pilots, $1,376 per hour on maintenance, and they burned 1,755 gallons per hour.

But wait, it's not so simple.

"It'll certainly cost far more raw dollars to fly that widebody, but simply put, you are spreading those costs" over longer trips and more customers, says Tim Smith, a spokesman for American.

Smith says airlines consider costs and potential revenue — how many seats are likely to be sold and at what price — when deciding what type of aircraft to use on a particular route.