It's been four days and the mystery of the missing Malaysia Airlines plane, flight MH370, continues, as the search teams from 11 nations have not been able to trace even a sign of the Boeing 700-200ER.

How could a jetliner carrying 239 passengers vanish just like that?

Its disappearance bears eerie similarities to that of the Air France flight AF447 tragedy - both were at cruising altitude above the sea, with a similar number of passengers (239 for MH370 and 228 for AF447, including 12 crew in both cases), and both did not send out a mayday call - although the last-heard words uttered by the pilots of both flights seemingly convey two vastly different scenarios: "All right, good night bye" as opposed to "Oh my God, we're going to crash. I can't believe it."

We trace back the Air France flight AF447 disaster:

When did the crash happen?

On June 1, 2009, Air France flight was en route from Rio de Janeiro to Paris when communications ended abruptly after it hit stormy weather. The Airbus A330-200 then plunged into the Atlantic Ocean.

There were no signs of problems with Flight AF 447 before take-off, and it was unclear whether the chief pilot was at the controls when it plunged into the ocean. Also, no distress call was made before the crash. However, the plane's system did send out an automatic message just before it disappeared, reporting lost cabin pressure and electrical failure.

How many passengers were there?

A total of 228 passengers were onboard the plane, including French citizens, Brazilians and Germans. Till today, the bodies of 74 passengers are still missing.

Last-heard words:

Oh my God, we're going to crash. I can't believe it

Which nations undertook the search-and-rescue efforts?

Brazil and France led the search mission, accompanied by the United States and Spain.

When was the wreck found?

The first piece of debris was found in the equatorial Atlantic on June 2. Shortly after, four more debris clusters were sighted 88km south of the fragments. The newly sighted debris included an unidentified metallic object 7m in diameter and a 19km-long oil slick.

"The nature of the debris, the concentration of the debris ... all combine to prove that the debris from Air France 447 has been found," said the French military spokesman Christophe Prazuck at the time.

What was the cause of the crash?

To put it simply, the formation of ice crystals in the airspeed sensors caused the autopilot to disconnect. The findings revealed that chief pilot Marc Dubois was taking a routine break when the autopilot disengaged, so the entire situation was managed by two junior co-pilots. Both of them struggled to stabilise the plane, with the senior pilot giving occasional commands.

A report released by French investigators on July 29, 2011 said: "The apparent difficulties in handling the aeroplane in turbulence in high altitude resulted in overhandling in roll and a sharp nose-up input" by the co-pilot.

This meant the jet was spiralling downwards at a speed of 55m a second - and the pilots had only 3 1/2 minutes to avert disaster.

The report by the Bureau of Investigation and Analyis in July 2012, said there was a "profound loss of understanding" among all three pilots about what was happening after the autopilot disconnected, and the errors that followed were the outcome of a confluence of factors beyond the competence of any individual pilot.

The entire process to closure took three years as investigation was heavily obstructed: It took nearly two years retrieve the black boxes, which hold the pilots' conversations as well as crucial data about controls and sensors, from the ocean bed.