Hard-liners have apparently won out at the Federal Aviation Administration, which is prepared to take quick action Monday if employes who belong to the Professional Air Traffic Controllers Organization go out on strike.

Officials at the FAA and Department of Transportation were split on how to handle the threatened strike. One faction felt that labor peace must be preserved at almost any cost. It feared even a short strike could inflict multimillion-dollar wounds on the economy and cause major disruptions (a half-million Americans take to the air every day) that could spell economic and political trouble for the Reagan administration, whose worst labor problem to date has been the baseball strike.

The nail-'em-to-the-wall faction argues that strikes against the government are illegal (penalty is dismissal, a $1,000 fine and/or a year and a day in jail), and that is that! They are anxious to deny PATCO (which has 15,000 of FAA's 17,000 controllers as members) a stranglehold over FAA and the airline industry.

Watching and waiting in the wings are employes, union leaders and officials of the U.S. Postal Service. The 600,000-member mail-moving corporation started contract bargaining seven weeks late (because the USPS tried to have one of the four unions designated as the bargaining agent), and the current contract expires July 20. If an air traffic controller strike can be avoided, or if PATCO gets a bloody nose, it could make militant postal leaders think twice about striking. By the same toden, if the strike comes and it is successful (would Uncle Sam slap 15,000 solid-citizen controllers in jail?) that could put added pressure on the postal service.

Except for a handful of total war advocates on both sides, nobody is anxious for an air traffice tie-up (it could stop or cripple 8 of every 10 commercial, freight and private flights) or for the mail to stop moving on July 21. Despite all the puns about the postal service, the only thing worse than getting bills (not to mention Social Security payments and the like) each month is not getting those bills!

A major side-effect of a serious postal strike could be the breakup of the government's first-class mail monopoly. There are many private corporations who would love to see the USPS fall on its face so they could take over some of its more lucrative business.

Top labor officials at the FAA, DOT and Office of Personnel Management have been huddling all week to hammer out what they will do, or not do, if a strike occurs. The Justice Department has been in on the talks, and the White House is monitoring the situation. And if you are planning to catch a business or vacation flight Monday, remember the advice here in the June 9 column. Take a couple of books to the airport, and be sure you have a ride home -- car, bus or whatever -- if things get sticky.