Thirteen months after they were fired for striking, only six of 11,400 former air traffic controllers have been ordered reinstated with back pay by the Merit Systems Protection Board handling appeals from the ex-aerial traffic cops.

So far this year MSPB judges have heard nearly 2,000 appeals, and has rendered decisions in about 60 cases. Based on the record to date, about one in every 10 controllers has been ordered restored to duty.

The Federal Aviation Administration is appealing all those back-to-work orders to the full MSPB.

The people who tentatively have won their jobs back -- controllers who formerly worked at the Leesburg Center near here, in Chicago, Dallas, New York and St. Louis -- basically argued that they were either not on strike, or were intimidated by coworkers into striking.

One individual ordered reinstated by the MSPB argued that although FAA had pictures of him on the picket line, he was there against his will. He said that coworkers threatened him if he did not join the strike, and claimed that he sent his family out of town during the August 1981 walkout by members of the Professional Air Traffic Controllers Organization.

PATCO officials repeatedly have denied that anyone was forced to strike.

One controller said that he did not return for work during the grace period set by President Reagan because he was vacationing in Europe and could not get back to the United States because of the strike.

Others have argued that they were sick at the time of the walkout, which resulted from a dispute over pay raises, retirement benefits and working and safety conditions.

FAA says that 11,400 of its 17,400 controllers were fired for striking. A total of 10,898 filed appeals with the MSPB, which was set up during the Carter administration to hear appeals from federal workers who believe they have been fired wrongfully.

MSPB currently is holding hearings around the nation -- from Charlotte, N.C., to Anchorage, Alaska. It hopes to complete hearings this year for nearly 10,000 of the controllers who want their jobs back.