(FORTUNE Magazine) – When the machinists at Eastern Air Lines went on strike last March, everyone figured that Frank Lorenzo, CEO of Eastern's parent, Texas Air, was about to lose his first big shoot-out. Nearly all of Eastern's 3,600 pilots walked out in sympathy, forcing the carrier to cancel more than 90% of its flights and file for Chapter 11 protection from creditors. But Lorenzo, 49, whom Fortune named one of America's toughest bosses in February, refused to back down. Now the pilots are weakening. While their union voted to continue the walkout, a stream of 250 defectors crossed the picket lines in one week. That gave Lorenzo enough pilots to meet his goal of getting 800 daily flights, two- thirds of the airline's prestrike schedule, into the air by year's end. Lorenzo, who declined to be interviewed, still faces turbulence. Eastern says it will lose $300 million in the second half of 1989. Union leaders argue that the airline is flying planes with inadequate maintenance, a charge that Eastern denies. The Air Line Pilots Association is contemplating a sympathy walkout at other carriers, a move that would benefit non-union carriers -- notably Continental Airlines, the other Texas Air subsidiary that Lorenzo controls. Once again, it seems, toughness has paid off.