Timeline of MH370 disappearance

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.

12:41 a.m.

Takeoff

All tracking systems are working as the Boeing 777-200ER takes off from the Malaysian capital of Kuala Lumpur, headed for Beijing.

1:07 a.m.

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.

The search for MH370

01:11 - Source: CNN

1:19 a.m.

Voice check-in

MH370 First Officer Fariq Abdul Hamid, left, and Captain Zaharie Ahmad Shah.

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.”

1:21 a.m.

Transponder off

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.

Two years after Malaysia Airlines Flight 370 went missing, a relative of one of the passengers burns incense in Beijing on March 8, 2016. Flight 370 vanished on March 8, 2014, as it flew from Kuala Lumpur, Malaysia, to Beijing. There were 239 people on board.

On July 29, police carry a piece of debris on Reunion Island, a French territory in the Indian Ocean. A week later, authorities confirmed that the debris was from the missing flight.

Staff members with the Australian Transport Safety Bureau examine a piece of aircraft debris at their laboratory in Canberra, Australia, on July 20. The flap was found in June by residents on Pemba Island off the coast of Tanzania, and officials had said it was highly likely to have come from Flight 370. Experts at the Australian Transport Safety Bureau, which is heading up the search for the plane, confirmed that the part was indeed from the missing aircraft.

In late February, American tourist Blaine Gibson found a piece of plane debris off Mozambique, a discovery that renewed hope of solving the mystery of the missing flight. The piece measured 35 inches by 22 inches. A U.S. official said it was likely the wreckage came from a Boeing 777, which MH370 was.

Relatives of the flight's passengers console each other outside the Malaysia Airlines office in Subang, Malaysia, on February 12, 2015. Protesters had demanded that the airline withdraw the statement that all 239 people aboard the plane were dead.

A police officer watches a couple cry outside the airline's office building in Beijing after officials refused to meet with them on June 11, 2014. The couple's son was on the plane.

Members of the media scramble to speak with Azharuddin Abdul Rahman, director general of Malaysia's Civil Aviation Department, at a hotel in Kuala Lumpur, Malaysia, on May 27, 2014. Data from communications between satellites and the missing flight was released the day before, more than two months after relatives of passengers said they requested it be made public.

Operators aboard the Australian ship Ocean Shield move Bluefin-21, the U.S. Navy's autonomous underwater vehicle, into position to search for the jet on April 14, 2014.

A member of the Royal New Zealand Air Force looks out of a window while searching for debris off the coast of western Australia on April 13, 2014.

The HMS Echo, a vessel with the British Roya; Navy, moves through the waters of the southern Indian Ocean on April 12, 2014.

A Royal Australian Air Force AP-3C Orion, on a mission to drop sonar buoys to assist in the search, flies past the Australian vessel Ocean Shield on April 9, 2014.

A relative of a missing passenger cries at a vigil in Beijing on April 8, 2014.

Australian Defense Force divers scan the water for debris in the southern Indian Ocean on April 7, 2014.

A towed pinger locator is readied to be deployed off the deck of the Australian vessel Ocean Shield on April 7, 2014.

A member of the Royal New Zealand Air Force looks at a flare in the Indian Ocean during search operations on April 4, 2014.

On March 30, 2014, a woman in Kuala Lumpur prepares for an event in honor of those aboard Flight 370.

The sole representative for the families of Flight 370 passengers leaves a conference at a Beijing hotel on March 28, 2014, after other relatives left en masse to protest the Malaysian government's response to their questions.

A member of the Royal Australian Air Force is silhouetted against the southern Indian Ocean during the search for the missing jet on March 27, 2014.

Flight Lt. Jayson Nichols looks at a map aboard a Royal Australian Air Force aircraft during a search on March 27, 2014.

People in Kuala Lumpur light candles during a ceremony held for the missing flight's passengers on March 27, 2014.

Malaysian Prime Minister Najib Razak, center, delivers a statement about the flight on March 24, 2014. Razak's announcement came after the airline sent a text message to relatives saying it "deeply regrets that we have to assume beyond any reasonable doubt that MH 370 has been lost and that none of those onboard survived."

Grieving relatives of missing passengers leave a hotel in Beijing on March 24, 2014.

A passenger views a weather map in the departures terminal of Kuala Lumpur International Airport on March 22, 2014.

A Chinese satellite captured this image, released on March 22, 2014, of a floating object in the Indian Ocean, according to China's State Administration of Science. It was a possible lead in the search for the missing plane. Surveillance planes were looking for two objects spotted by satellite imagery in remote, treacherous waters more than 1,400 miles from the west coast of Australia.

Satellite imagery provided by the Australian Maritime Safety Authority on March 20, 2014, showed debris in the southern Indian Ocean that could have been from Flight 370. The announcement by Australian officials raised hopes of a breakthrough in the frustrating search.

Another satellite shot provided by the Australian Maritime Safety Authority shows possible debris from the flight.

A distraught relative of a missing passenger breaks down while talking to reporters at Kuala Lumpur International Airport on March 19, 2014.

On March 18, 2014, a relative of a missing passenger tells reporters in Beijing about a hunger strike to protest authorities' handling of information about the missing jet.

U.S. Navy crew members assist in search-and-rescue operations in the Indian Ocean on March 16, 2014.

Members of the Chinese navy continue search operations on March 13, 2014. After starting in the sea between Malaysia and Vietnam, the plane's last confirmed location, search efforts expanded west into the Indian Ocean.

A Vietnamese military official looks out an aircraft window during search operations March 13, 2014.

Malaysian air force members look for debris near Kuala Lumpur on March 13, 2014.

Relatives of missing passengers wait for the latest news at a hotel in Beijing on March 12, 2014.