Beijing (CNN) -- It sounds like standard radio chatter between an airplane and ground control, mostly repeating the identifying number of the flight.
But the recording that Malaysian officials played for the first time in public in a Beijing conference room on Tuesday is purportedly the last known words of Malaysia Airlines Flight 370 before it disappeared on March 8.
"Malaysia three-seven-zero contact Ho Chi Minh 120.9, good night," says a voice identified by Malaysian officials as that of a radar controller in Kuala Lumpur, the Malaysian capital.
"Good night Malaysian three-seven-zero," answers a male voice believed to be a crew member on the plane.
Malaysian officials released the audio recording more than 50 days after the plane disappeared, in a long-awaited briefing before scores of relatives of the flight's Chinese passengers.
The session on Tuesday also included the release of a chronology of the aircraft's last known contacts with radar stations as well as a satellite orbiting over the Indian Ocean.
At 2:03 a.m. local time on March 8, the operational dispatch center of Malaysia Airlines sent a message to the cockpit instructing the pilot to contact ground control in Vietnam, said Sayid Ruzaimi Syed Aris, an official with Malaysia's aviation authority.
Sayid said flight MH370 did not respond to the message.
Nearly 20 minutes later, at 2:22, the Royal Malaysian Air Force picked up the flight for the last time on its radar system, Sayid said.
By that point, Sayid said, the plane was believed to have swerved far off course over the Malaysian coastal area of Penang, in the direction of the Malacca Strait.
According to Malaysian officials in Beijing on Tuesday, there was no direct communication between Malaysia Airlines and MH370 for a five-hour period, until the airline tried unsuccessfully to call the cockpit.
"At 7:13," Sayid said, Malaysia Airlines tried to "make a voice call to the aircraft, but no pickup."
If all had gone according to plan, MH370 would have landed at the international airport in Beijing at 6:30 a.m. on March 8.
Malaysian officials told Chinese families on Tuesday that, by their calculations, the aircraft would have run out of fuel seven hours and 31 minutes into the flight.
"Based on the fuel calculation ... the aircraft fuel starvation will occur at time 08:12," said Subas Chandran, a Malaysia Airlines representative.
The Malaysian delegation also published slides showing the last known "handshakes" between the aircraft and an Inmarsat satellite over the Indian Ocean.
The sixth and final handshake took place at 8:11 a.m. Malaysian time. According to these Inmarsat data points, in relation to the Inmarsat satellite, Flight 370 was far south of where it should have been if it had been on its planned route to Beijing.
The latest briefing marked a sharp change from previous combative meetings between Chinese family members and Malaysian officials.
The "families' committee" that has formed during the agonizing month and a half since the plane's disappearance has spent weeks demanding details on the aircraft's last known location.
Last week, more than 100 family members marched at midnight to the Malaysian Embassy in Beijing and staged a 15-hour sit-in demanding a meeting with a high-level technical delegation.
"They are making progress," said Jimmy Wang, a member of the families' technical committee, after Tuesday morning's briefing.