It took five days for search teams to find any debris the last time a passenger jet disappeared into thin air in June 2009. That was the ill-fated Air France Flight 447.
And the bulk of the wreckage was only found two years later in the vast Atlantic Ocean.
Now 60 hours after Malaysia Airlines (MAS) flight MH370 vanished from the radar, an international search and rescue team from nine countries have turned up nothing but oil slicks near a Vietnamese island and off Malaysia's east coast.
US authorities also say there was no sign of a mid-air explosion in the area when the Boeing jet was reported missing with 239 people on board, 40 minutes after it took off from the Kuala Lumpur International Airport last Saturday.
So, where is flight MH370?
"It is an unprecedented missing aircraft mystery," Department of Civil Aviation director-general, Datuk Azharuddin Abdul Rahman, told reporters at the airport in Sepang, today.
Malaysian authorities are hoping that tests on samples from the oil slick found 100 nautical miles off Kelantan could provide a clue to the passenger jet's whereabouts.
The results of the test is expected this afternoon, the third day of the search for the missing 11-year-old aircraft.
"We are every hour, every second looking at every area of the sea," Azharuddin said, as more ships and aircraft joined in the search that has expanded from the South China Sea to include the Andaman Sea and the Straits of Malacca.
Malaysian military officials said on Sunday that the plane, a Boeing 777-200ER, may have turned back from its scheduled route shortly before vanishing from radar screens, further deepening the mystery surrounding its fate.
Vietnamese authorities had said earlier that two floating objects were seen from the air late on Sunday, some 80 kilometres (50 miles) off Tho Chu island. Azharuddin, however, said Vietnamese officials had not yet confirmed to Malaysia whether they were indeed debris from the plane.
"There are various objects that we have seen, but none of them at this moment (have been confirmed to be) from this aircraft," he said.
Unlike the Air France crash which occurred in a rugged region that was as deep as 3,900 metres below the surface, MH370 flew over the Gulf of Thailand where the deepest point is about 80 metres.
The search should be easier for MH370, investigators and analysts say, but its location remains a mystery.
Most of them agree that the plane, which has a wingspan of almost 200 feet, would be noticeable if it landed anywhere in the area which is dotted mainly by small islands and oil rigs.
But the aircraft has yet to be found.
"We are looking at every angle. We are looking at every aspect of what could have happened," Azharuddin said.
"Again, we have to get concrete evidence... we have to find the aircraft," he added. – March 10, 2014.