American Airlines canceled nearly 600 more flights across the U.S. today as part of its MD-80 jet fleet remains grounded for maintenance checks. The carrier said it expects to have the last of its 300 MD-80s inspected and back in the air by late Saturday, raising hopes that its snarled route system will be back to normal by Sunday morning. Meanwhile, the parent of discount carrier Frontier Airlines became the fourth airline in a month to file for bankruptcy protection, although the Denver-based carrier said it would continue flying. For the full story visit http://www.latimes.com/business/la-fi-american12apr12,1,5746507.story
