Search for missing plane expands

KUALA LUMPUR, Malaysia (AP) — The search focus for a missing Malaysian jetliner is changing with India saying it is expanding its search to seas west of the Andaman Islands while the international hunt shifted toward the Indian Ocean.

The shift comes amid signs that the jet may have flown on for hours after last contact. It complicates the search by vastly expanding the area the lost jet might be. It follows remarks by a U.S. official that the Boeing 777 sent signals to a satellite for four hours after the aircraft went missing early Saturday. Vietnam says it has been asked by Malaysian authorities to consider sending planes and ships to the Strait of Malacca, also to the west of Malaysia.

Meanwhile, two U.S. officials tell ABC News the U.S. believes that the shutdown of two communication systems happened separately on Malaysia Airlines Flight 370. One source said this indicates the plane did not come out of the sky because of a catastrophic failure.

The data reporting system, they believe, was shut down at 1:07 a.m. The transponder -- which transmits location and altitude -- shut down at 1:21 a.m. This indicates it may well have been a deliberate act, ABC News aviation consultant John Nance said.

U.S. investigators told ABC News that the two modes of communication were "systematically shut down."

That means the U.S. team "is convinced that there was manual intervention," a source said, which means it was likely not an accident or catastrophic malfunction that took the plane out of the sky.