Refueling Stop Is Airline’s Weight-Reduction Secret : Noise limits: To comply with John Wayne Airport’s strict rules, some Alaska flights take off with less fuel.

Alaska Airlines has been interrupting flights from John Wayne Airport with unscheduled refueling stops in Ontario to reduce takeoff weight and stay within the county’s tough noise limits, the airline confirmed Tuesday.

Airline spokesman Greg Witter said about a dozen flights have made these unscheduled stops in the last two weeks, delaying flights by 20 to 40 minutes. Until a few days ago, passengers were not told of the Ontario stop until they were already at the gate, Witter said.

“We’ve had a handful of passengers who have complained,” Witter said.

Noise restrictions at John Wayne, among the nation’s toughest, require that airlines stay below specific quarterly noise averages as measured at various stations around the airport. The heavier the plane, the greater the noise because more engine thrust is needed to lift the aircraft.

Violators are subject to fines or other disciplinary measures. For example, airport officials recently postponed a new daily departure that had been granted to TWA because the carrier exceeded the noise limits a year ago.

“When an airline starts bumping the limits, they sometimes go to extraordinary lengths to avoid having a problem,” said Karen Robertson, the airport’s noise abatement officer. “They don’t want to lose the lucrative flights that they already have.”

The airlines are so anxious about losing flights, Robertson said, that many call the airport’s noise office after each takeoff to get instant noise readings off a computer screen linked to the county’s monitoring stations.

Most airlines using John Wayne Airport bump passengers or cargo off flights in order to reduce takeoff noise. Others block out seats so they cannot be sold. But Alaska is not alone in inserting a refueling stop, Robertson said. She declined to name other airlines that have done so, and it was not clear whether the other carriers have notified passengers in a timely fashion.

“We are a victim of our own success,” said Alaska’s Witter. “Our flights from John Wayne are full. They’re very popular.”

Seattle-based Alaska Airlines has a morning flight to Seattle and an evening flight to Portland. Each utilizes 136-passenger, McDonnell Douglas MD-80s.

To stay within noise limits, the airline might have to bump as many as 30 passengers at departure time. Pulling passengers off the evening flight to Portland, he said, would leave those people stranded.

But Tom Reedy, Northwest Airlines’ manager at John Wayne Airport, questioned Alaska’s strategy. “We control our passenger loads instead of the fuel,” Reedy said. “The passengers don’t like (adding a refueling stop), and we’ve found that it’s more costly.”

Witter said the Ontario refueling stops are a short-term solution to a seasonal problem. The airline is pushing the limits of its quarterly noise “budget” because summer is the peak travel season. In addition, the warmer weather requires that planes use more thrust to get off the ground. The new quarter begins Oct. 1.

Witter said the airline has been attempting in the last few days to contact passengers who have made their bookings in advance to advise them of the Ontario stopover. “We’re trying to reach them at least 24 hours in advance,” Witter said.

“It adds 20 to 40 minutes to a passenger’s flight time, and we recognize that this is an inconvenience,” he added, “but we thought people would prefer this to being bumped off the aircraft.”

Witter said more fuel is consumed when there are two takeoffs instead of one, but, he said, no cost figures were immediately available. Witter said the airline does not reconfigure its aircraft with fewer seats, as some carriers serving Orange County do, because the planes are also used in other air travel corridors.

Officials at Ontario International Airport could not be reached for comment.

One regional aviation official, however, said that despite Ontario’s infamous smog problem, the added flights there do not run afoul of any air pollution rules.

“I’ve never heard of another airline doing this,” said the official, Henry W. Wedaa, a Yorba Linda councilman who chairs the aviation committee of the Southern California Assn. of Governments, a six-county regional planning agency. “But it’s a legal way to get around the noise problem at John Wayne.

“It sounds unusual, but then Alaska Airlines has always had a reputation for being a bit zany.”