Northwest Airlines Corp. yesterday kept its planes flying for a third day since mechanics went on strike, boosting the company's bargaining power with unions and sending its shares and bonds higher.

The carrier completed 98 percent of its flights over the weekend, Fulcrum Global Partners analyst Susan Donofrio in New York said in a report yesterday, citing Northwest management. About half of Northwest's flights were delayed, some analysts said. Northwest shares rose 28 cents, or 5.2 percent, to $5.66 at 4 p.m. in Nasdaq trading.

"Northwest is in the lead right now," Darryl Jenkins, an adjunct professor at Embry-Riddle Aeronautical University in Daytona Beach, Fla., said in an interview yesterday. "They will be able to fly through this without too many problems."

The airline's plan to spend as much as $107 million to train 1,200 replacement workers and use outside contractors for some repair work paid off with no major disruptions over the weekend. The St. Paul, Minn.-based company still needs to win concessions from flight attendants and bag handlers. It wants further cost reductions from pilots, who already have agreed to some cuts.

Northwest officials did not comment specifically on Hawai'i flights, but Hawai'i Tourism Authority president and CEO Rex Johnson said there were no major disruptions. He said there was one cancellation over the weekend, and most flights to and from Hawai'i were on time.

The Associated Press reported that according to a union official, a flight from Seattle to Maui was diverted to Honolulu International Airport Saturday night after a gauge showed loss of oil.

All 230 passengers slept in a conference room at the airport because no available hotel rooms could be found, state Department of Transportation spokesman Scott Ishikawa said.

A Northwest reservations agent said flights out of Hawai'i yesterday were largely on schedule. Northwest's Web site showed a couple of flights to Honolulu were delayed about 10 minutes while one flight from Minneapolis was delayed about an hour and a half.

Northwest, which has posted $2.5 billion in losses over the past four years, is seeking to cut total annual labor expenses by $1.1 billion to stem losses and avoid a bankruptcy filing. It has won $300 million in cuts from pilots and managers and was seeking $176 million from the mechanics union. The company has said rising fuel prices make the cuts imperative.

The carrier, which is also seeking legislation that would allow it to defer contributions to its pension funds, has won fewer concessions from its workers than any other major airline.

"Even with the full $1.1 billion in labor concessions, the company faces major challenges as fuel prices continue to rise and the slow fall travel season approaches," Calyon Securities analyst Ray Neidl said in a report. The price of jet fuel has risen 52 percent this year.

Steve MacFarlane, the union's assistant national director, said the airline's maintenance difficulties will mount over time, particularly because the airline operates so many older planes.

"We never believed we were going to shut the airline down," MacFarlane said. "We knew this was going to take some time."

The nationwide strike by the carrier's Aircraft Mechanics Fraternal Association, which represents 4,200 mechanics, aircraft cleaners and building custodians, started with pickets at 35 U.S. airports on Saturday. The strike failed to draw sympathy strikes from other unions.

The airline's preparations for the strike, the first walkout against a major airline in seven years, were among the most extensive in recent history, analysts said. The company began planning 18 months ago.

"Northwest may have broken new ground," said Harley Shaiken, professor of labor relations at the University of California-Berkeley. "There are few examples where an employer has prepared as thoroughly as Northwest has. It seems Northwest wanted the strike as part of a plan to restructure."

The last strike against a major airline was in 1998, when pilots shut down Northwest for 15 days. A two-year mechanics strike at Continental Airlines Inc. that started in 1983 shut down the carrier for three days before some workers crossed the picket line to keep the airline operating.

While Eastern Air Lines Inc. was ready with replacement mechanics for a March 1989 strike, pilots unexpectedly honored the picket line and plunged the airline into bankruptcy.

"At the end of the day, Northwest has sent a message to the other labor groups," Roger King, an analyst at New York- based CreditSights, said in a report yesterday.

Northwest, which funnels most of its flights through its airport bases in Detroit, Minneapolis and Memphis, Tenn., planned to operate 1,473 flights yesterday in a scaled-back fall schedule. During the summer, Northwest operated an average of 1,600 daily U.S. flights, with more service on weekdays than weekends.

Joe Brancatelli, who writes for business travelers at JoeSent Me.com, said customers are unhappy with delays at Northwest. He said 46.5 percent of the 99 Northwest flights he followed on Saturday arrived on time. On Sunday, 53.5 percent arrived on time, he said.

"They are doing miserably," said Brancatelli, who is based in Cold Spring, N.Y. "I work for business travelers. They're worried about, are my flights running on time? Two-, three-hour delays are not acceptable."

Negotiations between Northwest and the union broke down last week after five months, mainly over the airline's proposal to fire all 600 of its cleaners and custodians and to pare mechanic jobs to 2,350 from 3,600.

No further negotiations are planned at this point. The National Mediation Board, which had been overseeing the talks, encouraged the two sides to return to bargaining.