Trans World Airlines Inc. won a major victory in its dispute with striking flight attendants yesterday when a federal judge in Kansas City, Mo., ordered thousands of machinists to cross the flight attendants' picket lines and go back to work.

By ordering the machinists to end their walkout, U.S. District Judge Howard F. Sachs made it easier for TWA to return to normal operations during the strike by 5,700 flight attendants.

Without the support of the machinists, the striking flight attendants lose much of their bargaining clout.

Negotiations between the Independent Federation of Flight Attendants and TWA are scheduled to resume in Philadelphia this morning.

The parties have not met since talks ended unsuccessfully Friday morning in Washington.

Before the judge issued the temporary injunction yesterday, the machinists' impact on TWA appeared to be strongest in Kansas City, where the airline does long-term maintenance on its airplanes, and at New York's John F. Kennedy Airport, the key departure point for TWA's flights to Europe.

Throughout the walkout, the International Association of Machinists and Aerospace Workers (IAM) has allowed its individual members to decide whether to work or honor the picket lines.

TWA said that about 80 percent of the machinists' afternoon shift reported for work in the Kansas City overhaul base yesterday.

On Monday, most machinists honored the flight attendants' picket lines in Kansas City.

TWA Chairman Carl Icahn had said he might sell or break up the airline if the machinists refused to go back to work.

Airline industry analysts said several domestic airlines would be interested in buying certain TWA assets, including its valuable overseas routes and the PARS reservation system.

Meanwhile, TWA officials said yesterday the airline operated 61 percent of its regularly scheduled flights, as the flight attendants' strike ended its fifth day.

TWA operated 11 of 26 regularly scheduled flights from the three major Washington-area airports, and plans to increase to 13 on Thursday.

The airline has replaced the striking flight attendants with 1,750 new hires and 1,500 supervisory personnel.

Icahn has said the new hires will not lose their jobs if the striking flight attendants return to work.

Icahn and IFFA President Vicki Frankovich debated the key issues last night on The MacNeil/Lehrer News Hour.

Icahn predicted that the court order sending the machinists back to work would enable him to win his battle with the flight attendants.

"I've thought all along that we were going to win this strike," Icahn said. "I think this decision certainly will speed that occurrence."

Icahn also said that when negotiations resume today, he will continue to demand that the flight attendants agree to work two additional in-flight hours a week and take a 17-percent wage cut.

Frankovich, who offered to take a 15-percent wage cut, said Icahn's work-rule demands would jeopardize passenger safety by forcing the flight attendants to work too many hours each month.

"We are attempting to protect ourselves from totally unreasonable and outrageous demands," Frankovich said.

"We offered a 15-percent wage cut and that is comparable to what other employes in the same wage bracket were forced to do. We offered to work an additional five hours a month," she said.

"We are away from home 240 hours a month to be in the air 70 to 75 hours a month." Frankovich continued.

"The additional work-rule changes we have offered would keep us away from home 260 hours a month. He has thrown around this figure of two hours of extra work in-flight a week," she said. "That would cause us to work 320 hours a month. It is totally unacceptable."

"The real question here is work rules," Icahn said.

"What we need and must have is productivity, this extra two hours per week.

"We cannot compete without this. We must have these concessions to exist," he said. "Those are the facts."

When talks between the flight attendants and TWA ended last Friday, there was disagreement over new work rules and the size of expected wage cuts.

TWA, which lost $193.1 million last year, said its machinists recently accepted a 17 percent cut in pay, while the airline's pilots agreed to a 26 percent cut.

The average salary of striking flight attendants is about $35,000, Icahn said.

Judge Sachs' decision in Kansas City yesterday increases the pressure on the flight attendants as the Philadelphia negotiations begin.

His decision was based on the new contract between TWA and the machinists, which includes a "no-strike" clause.

Sachs said a federal arbitration panel would be asked to review the contract and rule on whether the machinists must cross the picket lines.

However, he said previous rulings indicated that TWA would win the arbitration case.

A final ruling is not expected for about three weeks.

Sachs also asked the airline and the union to agree on a plan to notify union members of the injunction ordering them to go back to work.

In his six-page memorandum, Sachs concluded that TWA is entitled to a preliminary injunction "against the machinists union's further authorization of a work stoppage by its members or its participation in the flight attendants' strike against TWA."