Northwest Airlines Corp., the fifth-largest U.S. airline, emerged from bankruptcy protection today after filing for chapter 11 nearly 20 months ago, the Wall Street Journal reported today. The airline filed for bankruptcy in 2005 after it was weighed down by high labor costs, an old and overly large aircraft fleet, heavy debt and huge pension liabilities. It also faced rising fuel prices and expanding competition from discount carriers and restructuring network peers. The carrier — the last to step out of chapter 11 after a six-year industry downturn that sent many airlines into court protection — emerges with lower expenses, less debt, a smaller fleet and expectations of earning nearly $1 billion pretax this year and almost $1.4 billion in 2010. Based on “when issued” trading of its new shares in recent days at $25 a share, the market values Northwest at a lofty $6.9 billion. Northwest CEO Doug Steenland said that the airline’s two paramount goals are repairing employee relations and improving customer service.