KUALA LUMPUR: On the day Flight 370 vanished, air-traffic controllers and Malaysian Air struggled for hours to understand what was happening even as the country’s military watched the plane appear to reverse course.

The initial confusion was disclosed Thursday in Malaysian government documents tracing the start of a mystery that began March 8. Malaysian and Vietnamese controllers traded phone calls and relayed a tip from the airline that the jet may have gone to Cambodia, according to a log of the early actions in the case.

Earlier that night, the Malaysian military detected an unidentified radar target believed to have been the Boeing 777-200ER as it headed west across the country, according to a statement by Acting Transport Minister Hishammuddin Hussein.

“The aircraft was categorized as friendly by the radar operator and therefore no further action was taken at the time,” Hishammuddin said in the statement, which didn’t elaborate on any contacts with civilian authorities.

The statement and documents, including a preliminary report dated April 9, gave no new clues about why a beacon that helped mark the plane on radar went dark shortly before the jet aborted its route to Beijing from Kuala Lumpur with 239 people on board. Investigators have concluded it flew south toward Australia and crashed in the Indian Ocean after running out of fuel. The hunt for the 777 is the longest for a missing passenger jet in modern aviation history. The case has baffled authorities because radar contact was lost less than an hour into a routine trip, at 1:21 a.m. local time. No debris has been found in weeks of patrols by planes, ships and a robot submarine.

Malaysian Airline System Bhd. said Thursday it will make advance payments to the next of kin of Flight 370 passengers. The payouts won’t affect families’ rights to claim compensation later, and will be calculated as part of the final sum, the airline said in an e-mailed statement. The carrier didn’t say how much would be disbursed. Assistance centers for relatives set up around the world will close by May 7, and passengers are being advised to return to their homes and await updates on the investigation instead of staying in hotels, the airline said.

Malaysia has set up a team to probe the disappearance that will consist of three groups with specific focus areas, not including criminal investigation.

Meanwhile, Malaysia Airlines on Thursday advised relatives of the missing MH370 passengers to move out of hotels and return home to wait for news on the search for the missing plane.

Since the Boeing 777 disappeared, the airline has been putting the relatives up in hotels, where they’ve been briefed on the search. But the airline said in a statement Thursday that it would close its family assistance centers around the world by May 7, and that the families should receive search updates from “the comfort of their own homes.”