KUALA LUMPUR, Malaysia (AP) — Malaysian Prime Minister Najib Razak has called for real-time tracking of planes and improving their communication system to prevent a repeat of the mysterious disappearance of Flight 370.

In an opinion piece Wednesday in the Wall Street Journal, Najib called for changes that would “make it harder for an aircraft to simply disappear, and easier to find any aircraft that did.”

“One of the most astonishing things about this tragedy is the revelation that an airliner the size of a Boeing 777 can vanish, almost without a trace. In an age of smartphones and mobile Internet, real-time tracking of commercial airplanes is long overdue,” he said.

The Malaysia Airlines plane carrying 239 people was traveling from Kuala Lumpur to Beijing on March 8 when it disappeared. The search is focused in the Indian Ocean, west of Perth, Australia, but it has not been found.

Inmarsat Plc, a British provider of global mobile satellite communications services, said Monday it will offer free basic tracking services for planes flying over oceans. The service will be available to most of the world’s long-haul commercial fleet.

The Malaysian plane sent a signal to an Inmarsat satellite, but not location data. Engineers conducted a novel analysis of those signals to determine the plane’s flight path, but the effort took time.

Najib also urged the aviation industry to consider changing planes’ communications systems so that they can’t be disabled midair. The government has said someone severed the plane’s communication systems with the ground and deliberately diverted Flight 370.

He said the capacity of the cockpit data recorder, one of a plane’s two black boxes, should be extended from two hours currently to recording the entire flight, while its location beacons should be made to last at least 90 days, instead of 30 days now.

“The global aviation industry must not only learn the lessons of MH370 but implement them,” he added.

Najib reiterated that Flight 370 was one of world’s greatest aviation mysteries. “Nobody saw this coming, nobody knows why it happened, and nobody knows precisely where it is,” he said.

He said the government has done its best but admitted there were mistakes in the early days of the crisis, with a disorderly public communication and a slow start to search efforts. He said an independent investigation is ongoing so the government can learn from mistakes.

Najib assured families of passengers that Malaysia will “keep searching for the plane for as long as it takes.”

Australia is leading the search, which is moving into a second phase in which commercial underwater operators will be contracted to scour a vast expanse of seabed with sonar equipment looking for wreckage for the next one year.

An Australian ship on Tuesday returned to the area where underwater sounds consistent with black boxes were heard in April, the search coordination center said. The ship had returned to port briefly to be resupplied. The Ocean Shield is carrying a robot submarine, the Bluefin 21, to survey the ocean floor.

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