The United States believes that the shutdown of two communications systems on missing Malaysia Airlines flight MH370 occurred separately, indicating that it may have been a deliberate act, ABC News reported today, although other American officials said the Boeing 777-200ER had sent data for another four hours after vanishing from radar screens
According to the report, two US officials said that they believe the data reporting system was shut down at 1.07am, while the transponder was shut down at 1.21am on Saturday, when the flight carrying 239 people vanished from radar screens.
"This indicates that it may well have been a deliberate act," ABC news aviation consultant John Nance reportedly said.
The transponder is the device that transmits location and altitude.
The report said the US team is convinced that there was manual intervention, and that it was likely not an accident or malfunction, that caused the plane to go missing from the sky.
Earlier, it was reported that satellites had picked up faint electronic pulses from the Beijing-bound flight, after it went missing on Saturday, but the signals gave no information about where the stray jet was heading.
The United States, which is part of an international search for the missing jetliner, had also said that the search area may soon expand into the Indian Ocean, consistent with the theory that the plane may have detoured to the west about an hour after take-off from Kuala Lumpur.
From data supplied by Malaysian authorities, the US believes missing flight MH370 was flying for another four hours after contact was lost with it.
Contact is usually maintained through the Aircraft Communications Addressing & Reporting System, or ACARS, which allows the plane to maintain contact with ground stations via radio or satellite.
These unaccountable four hours of possible flying time necessitated the search and rescue operations to expand their coverage to cover the Indian Ocean too.