In the airline industry's dark months after the September 2001 attacks, the federal government, banks, aircraft lenders and others came forward to help, giving the wounded companies plenty of leeway in the face of extraordinary circumstances. But three years later, the benevolence is gone. In a form of tough love that is quickly spreading, these same backers are putting the clamps on the still-troubled airlines, particularly those operating under bankruptcy protection. The backers are giving chief executives at United Airlines, US Airways and ATA Airlines their marching orders: enforce strict timetables, conserve cash, reduce spending and eliminate jobs - or...