The Federal Aviation Administration may begin ordering cutbacks of some commercial airline flights to avoid overtaxing the air traffic control system, Transportation Department officials have told key airline executives.

Transportation Secretary Drew Lewis and FAA Administrator J. Lynn Helms told a group of airline executives at a private meeting Thursday that operations at the nation's 22 major airports, including National Airport, would be reviewed and could be reduced to the 50 percent level generally ordered by the government when the Professional Air Traffic Controllers Organization went on strike Aug. 3, according to industry sources.

The FAA plan has resulted in a system running at about 75 percent of its pre-strike level because most of the airports other than 22 major ones did not have to make major cuts in operations.

The FAA originally ordered the airlines to reduce the number of their flights at those 22 airports by as much as 50 percent, depending on the airport and the hours of operations. However, airlines did not have to reduce operations at those airports if they did not have more than one flight an hour.

Since the strike began, however, the FAA has allowed the airlines to add flights to their schedules if it appeared that they could be accommodated.

Because of those additions, the number of flights at the 22 airports can now range well above 75 percent of their pre-strike level, sources quoted Helms as saying. According to one airline source, Helms told the group that the system had expanded too fast since the strike and that the FAA needed to get a "pad" to avoid overtaxing it.

While Helms said safety isn't jeopardized by the current number of flights, meeting participants reported, he told them the increased flight activity and workload on the air traffic control system wouldn't give the FAA a "cushion" that would allow the FAA to reduce the controllers' 48-hour work week and give them the vacation time Helms had planned.

The added flight activity also wouldn't allow sufficient flexibility to accommodate the possibility of bad winter weather and the additional workload it generates.

"I guess they gave away more than they should have," one source said. "The system was allowed to be expanded beyond what they first planned and they want to get it back . . . ."

A DOT spokesman insisted yesterday there were no plans for a significant reduction in daily flights and that there was no discussion at the meeting of any "strain" on the system.

"We can handle more traffic now than 75 percent, but we want a cushion," Linda Gosden said.

The only flights that may be reduced at the 22 airports are some the airlines got permission to add on to the "50 percent" plan, she said, especially if an FAA review shows that some airlines have a "disproportionate share" of those extra flights.

Generally the additional flights have accounted for an average 1 to 2 percent increase in the number of flights over the "50 percent" plan at the key airports, she said.

Although Gosden acknowledged that some of the 22 airports have been operating at 75 percent of their pre-strike levels, she said they were generally operating at between 50 and 54 percent.

"Where an airport can handle the increase, we'll allow it," she said. But she noted that there has been a steady increase in the number of requests for extra flights and the FAA would like to cut down to allow the "cushion."

At the meeting, Helms indicated he hopes to make some changes by Oct. 25, the day of the major schedule changes for the airlines, but was asked by the airlines to give them a greater lead time so that changes could be incorporated into the Official Airline Guide generally used by the industry for flight information.

In response to complaints at the meeting about general aviation, Helms also is said to have promised to look into the numbers of private aircraft, even if they are not using the 22 major airports. The airline officials told him there are 2,600 airplanes used by the airlines, compared with 250,000 private planes.