American Airlines Chairman Robert Crandall, famed for his take-no-prisoners approach to competition, is at it again.

Yesterday, he took on the Federal Aviation Administration over what he says is an unfair competitive advantage granted to rival United Airlines.

The fight is over scheduling at Chicago's O'Hare International Airport, one of four airports nationally where the number of takeoffs and landings allowed each hour is limited by the FAA. American filed suit against the FAA in the U.S. Court of Appeals in Washington after the agency approved a schedule change that American says favors its arch rival, United.

The schedule change would allow some United flights to take off earlier than American flights -- a significant advantage in the cutthroat world of airline competition. Other things being equal, passengers and travel agents tend to pick the flight that leaves soonest when making travel plans.

"The FAA's decision blesses a 'sweetheart' deal struck behind closed doors in August between the FAA and United and allows {United} to leapfrog American's schedules at O'Hare at critical times of the day," said Anne H. McNamara, American's senior vice president and general counsel.

O'Hare is a major hub and lucrative market for both airlines. According to American, the changes approved by the FAA on the grounds that they would result in more efficient operations at the airport give United "an unfair and illegal competitive advantage."

Not surprisingly, United sees things differently. The changes, which become effective Oct. 1, "will allow United to continue with its plans to address delay and congestion issues at O'Hare which will benefit the traveling public," said United Chairman Stephen M. Wolf.