WHAT WE KNOW AND DON’T KNOW

The crash: Malaysian Prime Minister Najib Razak said satellite data received from the plane indicated it flew “to a remote location, far from any possible landing sites.”

Flight’s last position: Data have pinpointed the middle of the ocean, west of Perth, Australia as the last spot the flight was in the air.

Who and how: The airliner was deliberately turned back across Malaysia to the Strait of Malacca, with its communications systems disabled, Malaysian authorities say. The possibilities they are considering include terrorism, sabotage, catastrophic mechanical failure and the mental health of the pilots or someone else on board.

Signs of debris: The prime minister didn’t address whether floating objects have been found in the ocean.

Black box: Searchers are racing to locate the plane’s black boxes before a battery-powered ping they emit fades away. The boxes, which would help identify the cause of the crash, are able to send those signals for at least 30 days following a crash, depending upon the battery’s strength.

The locator: A one-metre-long cylindrical microphone is en route and will be towed underwater behind a ship. It will be able to pick up any black box ping emitted from about two kilometres away.