The Justice Department, which is investigating computerized airline reservation systems to see if they are anticompetitive, has asked the Civil Aeronautics Board to abandon a parallel inquiry into the subject.

The request came in an April 13 letter from Assistant Attorney General William F. Baxter, chief of the Justice's antitrust division, to CAB Chairman Dan McKinnon.

The CAB is in the final stages of deciding what, if anything, it should do about the computerized systems. The two largest are owned by American and United airlines but display the Baxter Asks CAB to Drop Own Air Ticketing Probe By Douglas B. Feaver Washington Post Staff Writer

The Justice Department, which is investigating computerized airline reservation systems to see if they are anticompetitive, has asked the Civil Aeronautics Board to abandon a parallel inquiry into the subject.

The request came in an April 13 letter from Assistant Attorney General William F. Baxter, chief of the Justice's antitrust division, to CAB Chairman Dan McKinnon.

The CAB is in the final stages of deciding what, if anything, it should do about the computerized systems. The two largest are owned by American and United airlines but display the schedules of many other airlines.

The central concern is that the American and United computers are programmed in a way that influences travel agents who lease the systems to book passengers on American or United rather than on other airlines offering similar schedules.

Baxter made the request, his letter said, to avoid "overlapping" investigations. The Justice Department has never explained the origins of its inquiry, but they are widely believed to be allegations that American Airlines used its computer as part of a "dirty tricks" campaign against Braniff before Braniff filed for bankruptcy last summer.

Since then, Justice has concluded a grand jury investigation in Fort Worth and filed a civil complaint against American President Robert Crandall charging that he attempted to fix ticket prices in a telephone conversation with Braniff President Howard Putnam that Putnam taped.

Justice is continuing a civil probe into the computer question. Baxter said in his letter that "a very significant aspect of the continuing investigation is possible anticompetitive use by American Airlines of its computer reservations system (CRS). In addition, a full-time investigation into possible anticompetitive practices associated with the United Airlines CRS has been underway for over a year. . . . "

Both American and United officials have said that, while there is no question their computer systems have a certain bias, that bias is not anticompetitive.

While Justice was working on its case, Congress asked the CAB to initiate its own inquiry. CAB staff told the board in public session yesterday that an initial report on the computer bias question will be completed in about three weeks and that the board will be offered a number of options on how to proceed.

McKinnon, asked about Baxter's letter, said, "We're in this because of the Congress and our first loyalty is to answer the Congress." The board could decide, he said, to do a full-scale investigation, simply hand over what it has to Justice, or initiate a rulemaking procedure.