United Airlines Inc., Delta Air Lines Inc., Continental Airlines Inc. and Southwest Airlines Co. cut 2008 U.S. capacity plans on mounting concern that rising oil prices and a weakening economy will erode earnings.

Delta, the third-largest U.S. carrier, also forecast Tuesday that higher fuel costs will wipe out a fourth-quarter operating profit. A 48 percent surge in jet fuel this year and the potential of slowing U.S. travel demand prompted the changes even as several carriers said traffic and unit revenue rose last month.