Malaysia Airlines steward Mohd Hazrin Mohamed Hasnan, 34, had missed the company bus so his wife drove him to Kuala Lumpur International Airport on the night of March 7. “We had the usual conversation and Mohd Hazrin held my hand and kissed it,” Intan Maizura Othaman, also 34, who is pregnant with their second child, later recalled.

“‘I love you’ were his last words.”

Together with five other stewards and four stewardesses, Mohd Hazrin was on duty on the red-eye flight MH370, scheduled to depart at 12.35am and arrive in Beijing at 6.30am.

MH370 was a relatively new Boeing 777-200ER, part of a family of long-range wide-body twin-engine jet airliners built by Boeing Commercial Airplanes. The plane had clocked more than 53,400 hours since it was delivered in May 2002, and had been given a clean bill of health after a maintenance check-up on Feb 23, 2014. Malaysia Airlines flew the KL-Beijing route twice a day.

In the cockpit that night was Captain Zaharie Ahmad Shah, 53, a father of three who had been with MAS for 33 years and had more than 18,000 flight hours under his belt.

Seated on his right was first officer Fariq Abdul Hamid, 27. The younger man, who was engaged to be married to a pilot from AirAsia, joined MAS seven years ago. He had clocked 2,763 flight hours and it was his first flight on a Boeing 777 as a fully approved pilot.

It was not a full flight — the Boeing 777 was configured to carry 282 passengers but there were just 227 on board. There were enough empty seats for some passengers to spread themselves out and enjoy more space.

Among those on board were vacationers in T-shirts, business executives with laptops safely switched off, construction workers heading home to China and two Iranian men who kept a low profile. Pouria Nour Mohammad Mehrdad, 19, and Delavar Seyed Mohammadreza, 29, were seeking a new life in Europe, on stolen European passports.

 

Clear skies, good night

According to flight communication transcripts released later, the plane was on the ground at 12.25am. This was when the cockpit made its first contact with KL air traffic control with the words “Delivery MAS370. Good morning.” Pilots say that typically, communication before and during take-off is handled by the first officer.

A minute later, at 12.26am, air traffic control handed the flight over to ground control as the plane moved away from its gate, or what is known in the industry as “aircraft pushback”.

The plane was designated Runway 32 for take-off. At 12.40am, the control tower gave the green light for departure and bade MH370 “good night”.

MH370 kept up constant communication with air traffic controllers as it climbed. Experts say there was nothing out of the ordinary in the chatter, based on the transcript.

Between 12.42am and 1.19am on March 8, KL air traffic controllers continued to guide the flight on its path. In the cockpit, the pilots would have been listening in to other conversations between air traffic controllers and other flights in the vicinity. This is standard procedure so pilots know who is flying above, below and nearby.

At 1.19am, MH370 was somewhere over the area where the Gulf of Thailand meets the South China Sea, travelling at 542 miles per hour at an altitude of 35,000 feet.

As it prepared to enter Vietnamese airspace, the final instruction came from Malaysian air traffic control. “Malaysian three seven zero contact Ho Chi Minh 120 decimal 9. Good night,” said KL. This was to tell Captain Zaharie and his co-pilot to switch to the designated radio frequency for Vietnamese air traffic control.

Five seconds later, someone from the cockpit of MH370 responded: “Good night Malaysian three seven zero.” Pilots say that under normal circumstances, it would have been the co-pilot signing off.

1.19am was the last time anyone on MH370 spoke to air traffic controllers.

Ho Chi Minh air traffic was standing by to receive the Beijing-bound plane. The usual drill is for pilots to call the new set of traffic controllers within a few seconds after leaving the first set, but when the skies are busy and air traffic controllers are talking to other flights, they wait and then try again.

Sometimes, pilots forget and air traffic controllers attempt to make contact. The communication gap can be up to three to five minutes, say those in the industry.

That night, air traffic controllers in Ho Chi Minh failed to get a response from MH370. They called on other flights near MH370 to call out, but no one got a reply despite a flurry of radio calls.

 

Just pings in the dark

At 1.31am - 12 minutes after the final contact with Malaysian air traffic control — Malaysian civilian radar sights the flight heading north-east across the Gulf of Thailand.

At 2.15am, Malaysia’s military radar picks up an unidentified blip — later confirmed to be MH370 — north-west of Penang. But this was shockingly far off its intended route.

The authorities also discovered something else sinister related to the plane’s communication systems, namely the transponder and Aircraft Communications Addressing and Reporting System (ACARS).

The transponder, a device in the plane which transmits data on location, altitude and speed to ground radar, was deactivated — most likely manually and deliberately — at 1.21am. Pilots say this is easily done with several clicks of a knob.

ACARS is a digital datalink allowing pilots to send simple short text messages transmitted through radio signals and satellites. It also sends data about engine performance to its manufacturers and automatically generates data on the technical condition of the plane. The messages are sent out by a plane every 30 minutes. To stop ACARS from transmitting data by radio, a series of cockpit switches must be flicked in sequence and some computer input is needed as well.

The last radio transmission from MH370’s ACARS was at 1.07am. At some point between that transmission and 1.37am, when the next transmission was expected, the system was also shut down — maybe even deliberately switched off in order to hide the plane’s position.

 

The tricky part about ACARS is its satellite transmission. To deactivate it, one has to get to an electrical panel that is not easily accessible. Investigators say this function was not switched off in MH370. It also explains why the plane continued to receive and respond to checks from a satellite once an hour.

Satellite data showed that the electrical system of MH370 was still functioning more than six hours after it lost contact with air traffic control.

London-based Inmarsat, which operates 10 satellites in geostationary orbit about 35,780km above Earth, said on March 14 that its network had picked up “routine, automated signals” from MH370. Satetllite “pings” were received from the missing plane as late as 8.11am on March 8.

Investigators calculated that based on the final “ping” from the plane and a stationary satellite, the plane had been flying in one of two air corridors stretching as far as Kazakhstan and Turkmenistan to the north or a southern one in the southern Indian Ocean around western Australia.

It was later determined that the plane flew along the southern corridor, and that its last position, at past 8am on March 8, was in the middle of the Indian Ocean, west of Perth.

By that time, if still in the air, the plane would probably have been almost out of fuel.