A Malaysia Airlines jet has gone missing over Southeast Asia with 239 people aboard.
Vietnam authorities said contact with Flight MH370 was lost near its airspace, but its exact location and what happened to it remained a mystery 12 hours after it slipped off air-traffic control screens.
Malaysia Airlines said the plane, on an overnight flight from Kuala Lumpur to Beijing, relayed no distress signal, indications of rough weather, or other signs of trouble.
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Meanwhile the search is continuing as relatives wait anxiously.
Malaysia Airlines has long been a respected name in regional aviation, enjoying an enviable safety record.
The incident will be a major blow to the airline, which has struggled to remain profitable recently against a host of nimble competitors, particularly the rise of budget airlines.
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The plane that disappeared Saturday somewhere over the South China Sea -- believed near Vietnam airspace -- was a Boeing 777-200, considered one of the safest planes in the industry.