An international fleet of search aircraft and ships is covering thousands of square miles in a bid to solve the mystery of the missing Malaysian Airlines Boeing 777.
But so far their efforts have proved fruitless. The airliner disappeared from radar screens on Friday night with 239 people on board. Not a shred of debris has been found in the search efforts since.
Malaysia's civil aviation chief called it an "unprecedented mystery".
How events unfolded:
Flight MH370 left Kuala Lumpur early on Friday evening, UK time, and was due to arrive in Beijing six hours later.
Around two hours into the flight, air traffic control lost contact with the aircraft over the South China Sea.
Now the search has been widened to the west of Malaysia amid reports the plane may have turned back.
Investigators are looking at several possible causes of the plane's disappearance. They include a possible act of terrorism, with authorities investigating two men who boarded the plane using stolen passports.
Another is a mechanical fault. The lack of wreckage found so far suggests a failure at high altitude, which means debris would be spread very widely.
The families of the 239 passengers on board are continuing to wait for news on loved ones.
Earlier, a floating yellow object and an oil slick seen in the sea were ruled out as possible links to the disappearance.