BEIJING, May 4 -- With engines roaring, two Chinese IL-76 transport aircraft took off from Australia's Perth International Airport Saturday, ending a 43-day mission searching for Malaysia Airlines Flight MH370.

This is an honorable retreat for the two planes, which arrived in Perth on March 22 as part of a Chinese air force detachment in support of the multinational search operation in the southern Indian Ocean.

On Thursday, Malaysia Airlines CEO Ahmad Jauhari Yahya said in a statement the world should face the fact that MH370's whereabouts remain unknown and the fate of all on board was still uncertain.

He said that, as there was still no trace of the ill-fated plane, the search operation in the southern Indian Ocean was moving to a new phase.

Yahya's statement echoed Australian Prime Minister Tony Abbott, who said Monday the hunt for the missing jetliner entered a new phase with the seabed search to be expanded to a much larger area.

With search areas having moved from the Gulf of Thailand to the North Indian Ocean and now to the South Indian Ocean over the past 57 days, the goal of this search effort, unprecedented in human history, remains the same -- to find MH370 and the 239 people on board as soon as possible.

Incomplete statistics show a total of 26 countries have participated in the search, with many vowing to dig out the truth no matter what and how long it takes.

SO HARD TO SAY GOODBYE

"Goodnight, Malaysian 370," an ordinary farewell message, has been confirmed as the final words from the cockpit of the ill-fated plane to air traffic control staff at 1:19 am local time on the morning of March 8. But it remains unclear whether they were the plane's last farewell words to the world.

The Boeing 777-200 aircraft was on its way from Kuala Lumpur to Beijing in fine weather, flying at an altitude of 35,000 feet. It was widely believed to be at the cruise stage of its flight in a safe and sound condition.

The 227 passengers on board, whose nationalities are different enough to resemble a mini "United Nations", include 154 Chinese, with the rest from more than 10 other countries including the United States, France, Australia and Indonesia, as well as a Malaysian crew.

None could have expected the expected end of the trip would never come.

The sun was already shining at 6:30 am local time on the runways of Beijing's Capital International Airport, where flights landed and took off with passengers coming and leaving.

For China and the whole world, it was nothing but a normal calm weekend.

Soon, the the airport's international arrivals screen indicated in red letters that MH370 was "delayed." Before long, Malaysia Airlines confirmed the jet had "lost contact" with ground control.

At noon, "delayed" was replaced by "canceled," meaning the plane had disappeared from radar screens.

Gripped by fear and grief, some waiting at the airport for family and friends on the plane to arrive began to sob and even wail.

With the first 24 hours after the tragedy regarded as the golden period for saving possible survivors, a rescue operation was immediately launched.

Chinese rescue workers, together with search forces from more than 10 countries, devised an emergency rescue mechanism and rushed to the Gulf of Thailand and the South China Sea, where the plane was presumed to have gone down based on an initial report from the Malaysian government.

Guided by multiple satellites, about 40 vessels and 40 aircraft joined the unprecedentedly massive hunt at an unmatched speed.

The search forces, working day and night in the air, on the sea and underwater, was branded by the Wall Street Journal as one of the largest-scale search efforts of recent years.

Despite all the tears and hopes, the first week of the hunt proved to be fruitless, due to the bewildering and sometimes even contradictory information given to the rescuers.

Since then, the endless wait has become torture for the families and relatives, who have gone through emotions from gut-wrenching grief to desperate longing of hope amid all kinds of speculation and rumors about key questions regarding the flight's possible direction, whereabouts and causes of its disappearance.

Their sufferings will sadly persist as the wreckage of the plane still cannot be located.