The nation's airlines kept about 60 percent of their scheduled flights in operation yesterday, as supervisors manned microphones and radar screens in place of striking air-traffic controllers, Federal Aviation Administration officials said yesterday.

At the FAA's request, carriers cut back flights from the normal 14,000 daily to about 8,000. Where possible, traffic peaks were smoothed out at 23 major airports around the country, as skeleton crews in control towers and regional "en route" centers took responsibility for routing aircraft.

Airline officials said most passengers were reaching their destinations, though often late and on consolidated flights. Most advised people planning to travel today to check with reservation offices in advance and be prepared for delays.

FAA Administrator Lynn Helms said about 29 percent of the country's 17,200 controllers reported to work on the morning shift, a figure that apparently held relatively steady through later shifts. He said that military controllers were on standby and that with them, supervisors and nonstriking personnel the FAA could maintain 60 percent flight operations indefinitely.

Striking controllers in the Washington area said the substitute crews were not technically qualified and advised the public not to fly. But Helms countered that the new crews were fully skilled and said "we absolutely will not allow airplanes to take off if there is any question of safety."

Through it all, institutions and people tried to cope.

For example, the U.S. Postal Service, which routes about a quarter of its express and first-class mail by air, was looking into its standby contracts with trucking firms. "It is going to cause some delays. There's no question about that, especially when you're talking about that mail that goes 500 miles-plus," said Postal Service spokesman Lou Eberhardt.

And around the country, as in Washington, business was up significantly at train stations, bus depots and car rental agencies away from airports.

The Washington area's three airports were noticeably quieter yesterday. National operated about 50 percent of its normal schedule of flights. Officials at Baltimore-Washington International reported traffic 68 percent of normal and Dulles International's levels were called not far below those of slow days.

Most major airports around the country were not as fortunate as Dulles, however. Chicago's O'Hare International, for example, canceled about 1,000 flights in and out, about half its normal load. At La Guardia Airport in New York, about a 50 percent reduction in operations was reported.

At airline headquarters, planners juggled schedules to save flights that were important for air connections or for which there were no alternative flights. Some canceled service for pets, unaccompanied children and baggage transfers. At least one -- New York Air -- inaugurated special "strike-saver" fares for passengers willing to sit out the delays.

Yesterday evening Helms said that the situation was "steadily improving." At 4:40 p.m. the emergency system was working well enough so that there were "no landing delays across the country," he said. Departing planes were experiencing about 20-minute delays, he said.

Initially, most private planes had been barred from the air if they required support from the air traffic control system. But as the day progressed, Helms said, the FAA's traffic-flow program worked well enough to allow more private planes in the air.

The FAA plans to reevaluate its traffic-flow plans this morning. Helms held out the possibility that if more controllers return to work and the weather is good (thunderstorms moved east from the Mississippi valley yesterday), flight levels by scheduled carriers might be increased to 75 percent of normal.

At National Airport, only two of 19 controllers scheduled to work on the 7 a.m. shift appeared for work yesterday. Emergency measures were implemented immediately to put supervisors on the controls in the tower and at the radar screens below, which track planes approaching and leaving the airport.

At Dulles, all 11 controllers on the morning shift failed to appear. At BWI, 12 of the 19 controllers scheduled to work were absent.

At the giant center at Leesburg, which directs aircraft at midflight, the turnout was larger. The facility's deputy chief, Ed Bland, said that 58 of the 100 controllers scheduled for the morning shift appeared and 63 of 104 reported for the afternoon shift.

Bland said that no supervisors or military personnel were manning the screens at Leesburg, only regular controllers. The center was handling without difficulty all airplanes routed through its 145,000-square mile sector, he said, although flight limitations had reduced traffic by about half from the normal 4,000 planes a day that the center handles.

Because of legal restrictions and possible friction with passengers, the controllers opted not to form picket lines at the area's three major airports. But about 150 strikers marched with signs outside the Leesburg center, jeering colleagues who passed through the gates to work in defiance of the strike.

Federal attorneys, meanwhile, obtained an injunction at U.S. District Court in Alexandria against area locals of the Professional Air Traffic Controllers Organization (PATCO), the controllers' union. U.S. marshals served notice of the injunction against Leesburg local president Tom Galloway as he picked the facility.

The president of the National Airport local, John Thornton, was served with the notice at his home in Virginia. He said that he would consult a lawyer before responding to the notice, but that he had no immediate plans to return to work without an acceptable settlement of the union's demands.

Eastern Airlines, National's largest tenant, meanwhile, canceled about 15 of the 45 departures it schedules daily at the airport. The New York shuttle flew on schedule through the morning but in the afternoon several flights were canceled, according to spokeswoman June Farrell.

American Airlines canceled seven of 25 National departures. "Those that are operating are operating with little or no delays," said American spokesman Paul Haney." We're getting people where they need to go."

United Airlines eliminated seven of its normal 21 departures at National, two of the normal 10 to BWI and one of the normal eight at Dulles. TWA flew 15 of its 18 scheduled departures at National and all of its three daily at Dulles -- although an evening flight into Dulles from Los Angeles was delayed five hours by the strike.

The strike meant better business for other means of transport. Amtrak official Bill Jackson reported that passenger levels ran about 30-35 percent above normal levels. Most Metroliners plying the New York-Washington route had two extra cars added, while at Union Station extra ticket agents and porters were on hand.

The Hertz rental agency assigned an extra staff member to its counter at the station and operated a shuttle bus to take people to the firm's L Street car storage area when cars at the station were all taken. Both Hertz and Avis reported many customers with reservations for cars at National asked to pick them up at the station instead.

In anticipation of airport "refugees," Greyhound added buses to the New York and Philadelphia routes. Trailways had extra ticket sellers on hand at its depot in downtown Washington.