WASHINGTON (Bloomberg) — US Airways Group Inc. and JetBlue Airways Corp. swung to fourth-quarter profits after losses a year earlier as they raised fares and still kept planes full.US Airways, which is pursuing a hostile bid for bankrupt Delta Air Lines Inc., posted a $12 million fourth-quarter profit after a $261 million loss. JetBlue had a $17 million profit after a loss of $42.4 million. Shares of both airlines declined after JetBlue forecast a loss this quarter and jet fuel rose.

Increased travel demand enabled US Airways to join 10 industry-wide price increases last year, while a new approach to managing fares lifted revenue at JetBlue, a low-cost carrier.

“It was a really good revenue environment out there,” analyst Ray Neidl of Calyon Securities Inc. in New York said in an interview. Higher fares lifted JetBlue’s operating margin, and “US Airways is a machine running well on all four cylinders right now,” Neidl said.

US Airways is the seventh-largest US airline by passenger traffic, while New York-based JetBlue is No. 8.

US Airways’ net income of 13 cents a share included $74 million of one-time charges. Without those costs, profit was 91 cents a share, beating the average estimate of 80 cents a share in a survey of eight analysts compiled by Bloomberg.

Profit of 10 cents a share at JetBlue trailed the 11-cent average estimate of 14 analysts compiled by Bloomberg. The shares fell 65 cents, or 4.5 percent, to $13.85 at 4 p.m. in Nasdaq Stock Market composite trading after the airline forecast a loss this quarter.

Shares of Tempe, Arizona-based US Airways dropped $1.33, or 2.4 percent, to $53.10 in New York Stock Exchange composite trading. Jet fuel for immediate delivery in New York Harbor rose 6.2 cents, or 3.7 percent, to $1.73 a gallon.

US Airways will drop its takeover offer if Delta’s official creditors committee doesn’t let US Airways examine the carrier’s books, start an antitrust review and delay bankruptcy proceedings, chief executive officer Doug Parker said yesterday.

Parker’s $9.87 billion bid for Delta that would create the world’s largest airline. US Airways has given Delta’s bankruptcy creditors until midnight on Thursday to act on its offer.

US Airways posted a full-year profit of $304 million, or $3.50 a share, compared with a year-earlier loss of $537 million, or $10.65 a share. The 2005 results didn’t include most of the gains from the carrier’s merger in September of that year with America West Holdings Corp.

US Airways increased fourth-quarter revenue 8.8 percent to $2.79 billion as it raised ticket prices paid per flown seat mile 5.5 percent.

“I think the old US Airways was so inefficient that this management team is going to find even more out there” and continue growing revenue, Neidl said. “If they had a bigger airline to work with, that management team would produce even larger profits.”For all of 2006, JetBlue lost $1 million compared with a year-earlier loss of $20 million as it scaled back capacity growth, cut fuel use and increased productivity.

For the fourth quarter, JetBlue increased its operating margin to 10.2 percent from a negative margin of 7.1 percent a year earlier. Sales rose 42 percent to $633 million as JetBlue reduced its offering of discounted fares.

“If we had a comeback airline of the year award, we’d have to at least be nominated for that,” chief executive officer David Neeleman said.