Editor’s Note: An earlier version of this story initially appeared on CNN.com in 2014.
New details provide a clearer chronology about what might have happened to Malaysia Airlines Flight 370 between its takeoff and its last known spotting seven hours later.
Here’s how experts and officials have reconstructed key moments of the flight, which disappeared March 8 with 239 people aboard.
All tracking systems are working as the Boeing 777-200ER takes off from the Malaysian capital of Kuala Lumpur, headed for Beijing.
ACARS sends communication
One of the plane’s communication systems sends what turns out to be its last transmission, according to Malaysia Airlines CEO Ahmad Jauhari Yahya.
“It showed nothing unusual. The 1:07 a.m. transmission showed a normal routing all the way to Beijing,” according to a statement from Malaysia’s Ministry of Transport.
The Aircraft Communications Addressing and Reporting System is the onboard computer that collects information – a lot of it – about aircraft and pilot performance. It’s akin to computers in automobiles that track oil levels and engine performance.
Aboard aircraft, ACARS computers measure thousands of data points and send the information via satellite to the airline, the engine manufacturer and other authorized parties, according to CNN aviation and airline correspondent Richard Quest.
The information is useful for operations, maintenance, scheduling and performance purposes, Quest said.
Someone in the cockpit makes a voice check-in with air traffic controllers as the plane is apparently leaving Malaysian airspace and entering Vietnamese airspace. Initial investigations indicate it was the co-pilot, Fariq Abdul Hamid, according to Malaysia Airlines officials.
“All right, good night” were the final words from the cockpit, said Zulazri Mohd Ahnuar, a Malaysian civil aviation officer.
The phrase “good night” is the radio parlance used by pilots when executing a handover from one airspace to another, Quest said.
“That is normal. That happens a gazillion times,” Quest said. ” ‘All right, good night’ is a pleasantry at the end of radio communication.”
The plane’s transponder stops communicating at 1:21 a.m., said Azharuddin Abdul Rahman, director of the Malaysian Department of Civil Aviation.
A transponder sends electronic messages from the plane: “squawks” to radar systems about the flight number, altitude, speed and heading.
This is enormously useful information to air traffic controllers who are looking at scores of blips on their screens, and each blip is a plane emitting identifying information, thanks to the transponder.