American May Slash Business Travel Fares : Transportation: Travel agents expect the airline to unveil the plan at briefings Thursday. The airline refused to comment.

American Airlines is expected to announce on Thursday a dramatic cut in unrestricted coach fares used primarily by business travelers, according to travel agents.

The fare cuts could be as deep as 40%, said travel agents who have been asked to attend a Thursday morning briefing at American’s headquarters in Dallas and other sites across the country.

But American, the nation’s largest airline, would also eliminate special corporate discounts that range as high as 35%.

An American Airlines spokeswoman declined to comment.

The fare cuts could fall apart if other carriers, notably United and Delta, fail to go along, industry observers said. But given American’s size and a slump in business travel, the other airlines would be under tremendous pressure to match the cuts if the response to the lower fares is positive.

Business travel dropped off last year in the face of recession and the Gulf War. The U.S. Travel Data Center estimates that business trips fell 8% in 1991, while travel in general remained flat. That was especially bad news for airlines, which count on business travelers to pay full fare, while their leisure travelers take advantage of discounts.

A large fare cut “would be fantastic,” said Mary Ellen Kelly, a Los Angeles corporate travel manager. The current coach discounts “are great only if you are planning a leisure trip.”

But Jay Anderson, vice president of USTravel, an agency based in Orange, said he wonders how the airline could maintain its level of service with much lower fares. He also noted a recent hike in energy prices, which could boost airline fuel costs.