The pilots of a Southwest Airlines jet struggled to handle the plane after an engine blew apart at 32,000 feet over Pennsylvania last month.

Investigators say the captain, Tammie Jo Shults, took over control from the co-pilot. She first asked air traffic controllers for permission to land at the nearest airport, but then aimed for Philadelphia, where the crippled plane made an emergency landing.

The National Transportation Safety Board provided new details Thursday on the fatal accident aboard Southwest Flight 1380 on April 17.

Investigators say they found pieces of the broken engine fan blade suspected of triggering the accident when it snapped off due to metal fatigue or microscopic cracking. They say the other blades in the engine were nicked during the accident but showed no signs of cracking.

(AP)