Malaysia Airlines Flight 370: How does a plane just disappear like that?

Malaysia Airlines Flight 370, carrying 239 people, suddenly disappeared on its way to Beijing from Kuala Lumpur. Under what circumstances can a plane drop off the radar?

Lai Seng Sin/AP Photo
People prepare to release a sky lantern during a candlelight vigil for passengers aboard a missing Malaysia Airlines plane in Kuala Lumpur, Malaysia, Monday, March 10, 2014. The search operation for the missing Malaysia Airlines Flight MH370 which has involved 34 aircraft and 40 ships from several countries covering a 50-nautical mile radius from the point the plane vanished from radar screens between Malaysia and Vietnam continues after its disappearance since Saturday.

It has been more than three days and no one yet seems to know exactly how Malaysia Airlines flight MH370, which was carrying 239 people, suddenly disappeared on its way to Beijing from Kuala Lumpur.

What we do know is that two hours after take-off, at about 35,000 feet, off the coast of Kota Baru, Malaysia, the Boeing aircraft dropped off the radar. Recordings from the radar also show that "there is a possibility the aircraft did make a turnback," said Rodzali Daud, the Royal Malaysian Air Force chief, according to Reuters.

The plane "lost all contact and radar signal one minute before it entered Vietnam's air traffic control," at 1:30 a.m. Lt. Gen. Vo Van Tuan, said deputy chief of staff of the Vietnamese army.

There are two ways in which an aircraft can register on radar. Primary radar works by bouncing radio waves off the body of the aircraft. Secondary radar works by having a transponder on the plane automatically transmit a unique signal whenever it is pinged, says Larry Cornman, scientist at the National Center for Atmospheric Research.

The strength of the signal is largely dependent on where the radars are placed in relation to the aircraft. If an aircraft is too far away from the radar, the signals are going to get weaker, Dr. Cornman says.

Harsh weather conditions such as heavy rains or thunderstorms and large geological features such as mountains can also interfere with radar signals. 

In areas with limited radar coverage, many large aircraft make their presence known through an automatic dependent surveillance-broadcast, in which the plane determines its location via global navigation satellites, which it then broadcasts on a radio signal. 

As what might have happened to the Malaysian aircraft, many theories are floating around.

An expert who spoke with Bloomberg said, "If it broke up at altitude there would be a wide debris field and you’d have seat cushions, insulation and other plastic from the cabin lining scattered for miles,” he said. “I’m really surprised they haven’t found any floating debris.”

Ocean currents could have also spread the debris far from impact, Cornman says. It is only a matter of time before one finds the wreckage from the aircraft, he adds.

But Dr. Cornman rules out any mishap caused by weather conditions because the sky seemed to be clear in this case, unlike the Air France Flight 447 flight that plunged into the Atlantic killing all 228 people on board.

It took five days to locate the floating wreckage from the Air France flight, and it was another two years before the aircraft's black box was retrieved from the ocean floor.

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