Airline capacity shifts: Bigger planes, fewer flights

Time's about up for United's fleet of 50-seat regional jets; other airlines are dumping them, too.

Just as airlines carefully price tickets—often day to day—to maximize their revenue and avoid unsold seats, they also massage their capacity to keep planes full. The past few years, with high fuel costs and weak economies led to fewer choices and fuller planes.

Now, with fuel prices much lower and more people willing to spend, a number of airlines are still hedging bets by changing their fleet mixes.

For instance, a few days ago we wrote here that United had swapped orders at Boeing, taking 10 777s in place of 787s; the larger plane has more seats to sell, and right now they are selling. United is also getting rid of some 50-passenger regional jets; they're fuel-burners and more seats can be sold.

Today, United announced that it will lease 11 used A319s, with options for 14 more. They will replace 70-seaters on some routes, and the 70-seaters will fly where the 50-seaters did. By using two 120-seat A319 flights in place of three 70-seaters, United gains 30 seats a day and burns less fuel. But, passengers will lose some flexibility.

American has also been fleet-shifting, accelerating the retirement of both its old MD80s and some smaller regional jets. And Southwest, whose fleet is entirely based on 737s, has just announced that it is shifting all its upcoming 737-700 orders over to 737-800s, which come with 32 more seats per plane. By the end of next year, Southwest will have 135 -800s, about 20% of the fleet.