The first officer of Malaysia Airlines flight MH370 has been identified as having made the last communication with air traffic control at 01.19 a.m. local time. “All right, good night,“ he stated when the aircraft was nearing the IGARI waypoint and was about to be handed over to the Ho-Chi-Minh-City ATC center in Vietnam.

Malaysian officials backed away from a statement made on Sunday when they had confirmed that the ACARS system had been turned off before the last contact with ATC. They now say that the last ACARS message has been received at 1.07 a.m. and the next one would have been due 30 minutes later, but never arrived. Given that the last contact with ATC was made at 1.19 a.m., it is possible that ACARS was turned off before that or later. MH370 had been seen on secondary civil radar for the last time at 1.21 a.m., before coverage became patchy and was lost altogether at 01.30 a.m.

Given the newly released timeline, it is also possible that all systems had been manually disabled after the last conversation with ATC.

MH370, a Boeing 777-200ER was on a scheduled flight from Kuala Lumpur to Beijing on March 8 when it disappeared from radar about 40 minutes after take-off. 239 people were on board.

The search and rescue effort now involves 26 countries. Two arcs have been identified as possible areas where the aircraft could have come down. They are identified by what is believed to have been the last known position over the Strait of Malacca and calculations on minimum and maximum speed.

At minimum speed for the Northern arc, the aircraft would have been over Laos and at maximum speed over the Caspian sea. For the southern arc, minimum speed would have taken the aircraft to the West of Sumatra and maximum speed way to the South of the Indian Ocean and significantly West of Australia.

According to Malaysia Airlines CEO Ahmad Jauhari Yahya, the aircraft is calculated to have had fuel for another 30 minutes flying depending on speed after the last time contact has been established with an Inmarsat satellite. No data had been exchanged so the position at that time is unclear. MH370 was last detected at 8.11 a.m. local time on March 8, around 7.5 hours after take-off and what appears to be close to when trip and extra fuel for the Beijing route would have been consumed.

Malaysian officials now believe someone on board had taken control of the aircraft, and there are diverging opinions about whether one of the pilots or another person should be suspected. Homes of the pilots were searched over the weekend.

Malaysian Chief of Police, Khalid Abu Bakar, said “We are now looking at one of four possible scenarios. These are sabotage, terrorism, highjacking and personal problems.”

Yahya said MH370’s suspected flight plan, as reconstructed from radar and satellite data, had been flown in a 777 flight simulator. “It confirmed it was possible for it to fly that,” he said.