Jan. 29 (Bloomberg) -- Northwest Airlines Corp., JetBlue Airways Corp. and AirTran Holdings Inc. posted fourth-quarter losses as rising fuel costs erased gains from fare increases.

Northwest said its deficit was $8 million after a $267 million year-earlier loss in bankruptcy, while JetBlue's $4 million loss compared with net income of $17 million. AirTran pared its loss to $2.17 million from $3.55 million.

Fuel is ``the principal culprit,'' said Dave Swierenga, president of consulting firm AeroEcon in Round Rock, Texas. ``The softening economy is clearly also having a negative effect.''

Today's results from the three carriers echoed those reported earlier by larger rivals including American Airlines and United Airlines, which also blamed fuel for blunting benefits from higher fourth-quarter ticket prices.

JetBlue jumped the most since 2002, leading the Bloomberg U.S. Airlines Index, as its loss was narrower than analysts expected. The shares rose $1, or 20 percent, to $5.94 at 4 p.m. New York time in Nasdaq Stock Market composite trading.

Northwest gained 65 cents, or 3.6 percent, to $18.59 in New York Stock Exchange composite trading, while AirTran rose 38 cents, or 4.5 percent, to $8.84.

Northwest, the fifth-largest U.S. airline, and other big carriers raised fares six times last quarter to counter a 43 percent jump in average jet-fuel prices. The major airlines also doubled their fuel surcharges to $40 round trip. The surcharges are supposed to be temporary.

Northwest

Northwest's loss was 3 cents a share, narrower than the loss of 8 cents projected in a Bloomberg survey of nine analysts. Sales at the Eagan, Minnesota-based airline rose 3.9 percent to $3.1 billion.

Northwest said it would have broken even except for a $14 million pretax loss from selling its remaining holdings in commuter carrier Pinnacle Airlines Corp. The quarterly deficit was Northwest's first since leaving bankruptcy in May.

Spending on fuel rose 16 percent to $937 million, making it Northwest's largest cost and helping to boost operating expenses by 4.3 percent. Higher prices were partially offset by a drop in fuel consumption as Northwest retired older, less-efficient planes and reduced mainline capacity by 2.5 percent.

The surge in fuel is spurring calls by investors for airlines to consolidate and pare expenses. Northwest is considering a tie-up with Delta Air Lines Inc., according to Northwest's pilots union. The airlines have declined to comment on any merger talks.

JetBlue

JetBlue's net loss was 2 cents a share compared with profit of 10 cents a year earlier. Sales rose 17 percent to $739 million. The New York-based discounter was expected to post a loss of 5 cents a share, the average of 13 analyst estimates compiled by Bloomberg.

The airline, No. 8 in the U.S. by passenger traffic, is trimming its 2008 capacity expansion for a second time. Seating will rise in a range of 5 percent to 8 percent compared with an earlier plan for growth of 6 percent to 9 percent, JetBlue said. The carrier will sell four more Airbus SAS A320 jets, in addition to two planes announced earlier.

Throttling back on adding capacity is ``prudent action in today's environment,'' Chief Executive Officer David Barger told analysts on a conference call.

Passenger traffic increased 7.1 percent last quarter as the airline boosted capacity 12 percent. As a result, the carrier filled an average of 77 percent of the seats on its planes, down from 80 percent a year earlier.

AirTran

AirTran, the low-fare airline that flies mostly in the eastern U.S., narrowed its loss to 2 cents a share from 4 cents a year earlier. Analysts predicted a 1-cent loss. Sales at the Orlando, Florida-based carrier rose 27 percent to $583.8 million.

A 35 percent jump in the airline's fuel bill, along with an 11 percent increase in labor costs, ended a string of three profitable quarters. AirTran raised fares three times in the fourth quarter.

AirTran sees a ``very challenging business environment'' for 2008, while advance bookings ``look strong,'' Kevin Healy, senior vice president of marketing and planning, said in a statement.

AirTran today forecast a 10 percent to 11 percent increase in capacity for 2008, and new Chief Executive Officer Robert Fornaro said it is ``likely we will reduce'' that goal should fuel costs remain high. In October, the carrier reduced its initial target for a 13 percent capacity expansion.

To contact the reporter on this story: John Hughes in Washington at jhughes5@bloomberg.net;

Last Updated: January 29, 2008 16:14 EST