A day after a trio of large U.S. carriers reported mixed earnings results, three more airline majors weighed in with their own financial reports Thursday, once again providing inconsistent signals from the sector.

Delta Air Lines

(DAL) - Get Report

reported fourth-quarter earnings today that fell 2 cents short of analysts' expectations, while competitor

Northwest Airlines

(NWAC)

beat Wall Street's fourth-quarter estimates by 3 cents. And

UAL

(UAL) - Get Report

, the parent company of

United Airlines

, blew away the forecast. However, all three carriers indicated that bad weather and labor unrest hampered their performance in the latest quarter.

Shares of Delta gained $1.50, or 3.2%, to $47.88 in recent

New York Stock Exchange

trading, while UAL rose $1.94, or 5.1%, to $39.81, also on the Big Board. Northwest lost $1.19, or 4.1%, to $27.69 in late

Nasdaq

activity.

Excluding unusual items, Delta reported earnings of $79 million, or 60 cents a diluted share, for the fourth quarter ended Dec. 31, down from $171 million, or $1.22 a share, for the same period last year. Eleven analysts surveyed by

First Call/Thomson Financial

expected the Atlanta-based company to post earnings of 62 cents a share.

Delta cited severe weather and labor troubles with its pilots' union for the decline in earnings. Revenue rose to $4.02 billion from $3.68 billion a year ago.

Northwest reported fourth-quarter earnings of $31 million, or 34 cents a diluted share, excluding nonrecurring items, up from $29 million, or 31 cents a share, one year ago, exceeding analysts' estimates of 31 cents.

Northwest, based in Eagan, Minn., also reported total fourth-quarter revenue of $2.74 billion, up from $2.56 billion for the same quarter one year ago.

UAL dramatically surpassed Wall Street's lowered expectations, posting a loss of $124 million, or $2.41 a share, excluding one-time items. Analysts expected UAL to report a loss of $3.74. For the same period last year, UAL earned $100 million, or 59 cents a diluted share, excluding items. Revenue rose 6.9% to $4.79 billion from $4.48 billion a year ago.

The airline, which is based in Chicago, said "our solid revenue performance could not offset our higher costs, which were driven primarily by substantially higher fuel and labor costs."