Investigators are starting to weed out theories about what caused Air France Flight 447 to crash, said Matthew L. Wald in The New York Times. Brazilian military search planes have spotted four more debris clusters about 55 miles from the first bits of wreckage, which were spotted in Atlantic Ocean on Tuesday. There was also a 12-mile oil slick, which rules out a midair explosion because that would have burned up the airliner's fuel.

Air France Flight 447 may have stalled after slowing down too much as it entered a zone of turbulence, said Charles Bremner in the London Times. Airbus, maker of the jet that crashed, has advised crews flying its A330 jets that they need to maintain adequate thrust when entering heavy turbulence, France's Le Monde reported. That could mean that investigators "have evidence that the aircraft slowed down too much, causing a high-altitude aerodynamic stall."

Maybe, but don't discount the possibility of a bomb, said Britain's Daily Telegraph. "One anonymous Air France pilot suggested that a bomb could 'very well' be the cause of the crash," which killed all 228 people on board during a flight from Rio de Janeiro to Paris. The scattering of the debris suggests that Air France Flight 447 broke apart at high altitude. Depressurization after even a small blast could cause that, although investigators think it's "extremely unlikely" that a bomb caused the crash.