Business Notes AIRLINES

U.S. airline fares are behaving like a jetliner climbing out of a tailspin. After tumbling some 12% since 1981, the cost of flying has risen by about 10% in the past three years and by around 6% so far this year, even though passenger traffic has been flat. The price hikes have stirred the suspicion of the Justice Department, which launched an antitrust investigation into possible collusion among the nation's major airlines. The Justice probe is seeking to determine whether the fare hikes were economically justified or the airlines acted in concert to raise prices.

The investigation was triggered by the announcement on Sept. 18 of an American Airlines fare increase. Within several days, eight other carriers, including United and TWA, followed suit. The airlines deny the possibility of collusion, insisting that fare decisions are made independently. But critics charge that the carriers use their sophisticated computerized reservation systems to signal pricing intentions to rivals.