Controlling heavy air traffic -- keep planes on ground or in the air?

The Federal Aviation Administration (FAA) plans to peel away most air traffic restrictions imposed after the air controllers' strike. But many pilots are hoping the agency will drag its heels on its plan to return to air delays rather than ground delays to control the flow of airport traffic.

Under the system of ''flow control,'' put on during heavy traffic, planes tend to be held on the ground before takeoff rather than put in an air holding pattern before landing. This system was actually in use for some years before the August 1981 strike. Its advantages: fuel saving and added safety in the event of bad weather.

The airline industry, concerned that too much ''flow control'' could cut down on flight volume and earnings, has been critical of the FAA for not moving away from the restriction faster. But many pilots say the now-mandatory action works so much better than when the decision of where to hold air traffic is left to the controller that they hope they never go back to the old system.

''It's a super situation,'' says one Chicago-based TWA pilot. ''I don't know why we didn't go to it a long time ago.''

But the official stance of the Air Line Pilots Association (ALPA) is more guarded:

''We want the system to be restored to its normal capacity (lifting peak-hour flight quotas now imposed in the nation's busiest airports),'' notes ALPA spokesman John Mazor. ''But if there's going to be a delay, we'd much rather have it when the plane is sitting safely on the ground.''

FAA administrator J. Lynn Helms has acknowledged that the move away from flow control - while desirable - will have to be made very slowly. He notes that newly trained controllers have had little experience in keeping stacks of planes circling while waiting for clearance to land. He wants controllers to develop the skill gradually by putting first a few and later several planes into holding patterns.

So far, ALPA credits Mr. Helms with striking the right degree of balance in his plan for action.

''We primarily want to make sure that any increase in the level of air traffic is equal to the ability of existing personnel to handle it safely,'' Mr. Mazor confirms. ''We want to keep them closely matched, and so far the FAA, which really shouldn't be in the business of clamping down on flow control and slots, has done it.''