US officials believe that two communications systems aboard Malaysian Airlines flight 370 were shut down separately, 14 minutes apart - which indicates the plane did not come down because of a sudden catastrophic failure. The data reporting system was shut down at 1.07 am and the transponder was turned off at 1.21 am just after the the pilot signed off to Malaysian air traffic controllers with 'All right, good night,' and before the Boeing 777 apparently changed course and turned west.
According to investigators this indicated that the switch-off could have been a deliberate act and officials told ABC News that the two communications devices were 'systematically shut down'. That has led the US investigating team to become 'convinced there was manual intervention' which in turn means it was not an accident or massive malfunction that caused the plane to cease to be airborne.
Despite these two crucial tracking devices being inoperative, the plane still sent signals to a satellite after the aircraft went missing in the form of 'pings' - rather like a cellphone does, even if it is not switched on. The Wall Street Journal reported that the 'pings' sent from missing flight 370 provided the plane's location, speed and altitude for at least five hours after it vanished from radar.