ATLANTA - Delta Air Lines Inc. said yesterday that it will reduce pension contributions for about 66,000 workers and change the way those retirement benefits are paid, to save up to $500 million over the next five years.

Delta will be able to reduce contributions by changing June 30 to a "cash balance" plan that provides a lump-sum payment, or annuity, when a worker leaves Delta, spokeswoman Peggy Estes said. The affected employees, who include all workers except the airline's pilots, now have a "defined benefit" plan with specified monthly payments. Estes wouldn't say how much the company is cutting its contributions.

The third-largest U.S. airline is seeking to reduce costs to stem losses, including $909 million in the first three quarters of this year. Most major U.S. airlines have had losses since last year's Sept. 11 terrorist attacks worsened a slump in air-travel demand. Delta said it lowered costs $1 billion this year and wants to trim $2.5 billion from 2003 through 2005.

With the pension change, Delta is "not going to guarantee to make up any shortfalls," said Robert Kemp, an accounting and finance professor and associate dean at the University of Virginia's business school. "They're trying to cut off the uncertainty on discount rates" and avoid cost-of-living increases.

Delta isn't cutting benefits for those who are retired, Estes said.

The carrier's pilots won't be affected because their pension plan is covered by an agreement with the Air Line Pilots Association. Most other Delta employees are nonunion; the company has the lowest percentage of union workers among major U.S. carriers.

Workers hired after June 30 will be eligible for only the "cash balance" plan, which limits the retirement benefit to the value of each worker's pension account, she said. Those who retire after June 2010 also will be able to take their money only under the new plan.

Those who retire between June 30 of next year and June 2010 can receive payments under the existing plan, with specified monthly payments, Estes said.

Delta will have a "substantial" expense this year because of a shortfall in its pension plans, the airline said last week in a Securities and Exchange Commission quarterly filing. The company didn't provide a figure.

The airline has 9,000 to 10,000 pilots. Delta employed 76,000 as of Sept. 30, the company said in a Securities and Exchange Commission filing.

The company said last month that it would cut as many as 8,000 jobs, or 11 percent of its work force, because of its losses.

Delta shares rose 14 cents to $11.03 yesterday in New York Stock Exchange trading. They have declined 62 percent this year.