Authorities said weeks ago that an unidentified person told traffic control, "all right, good night," before the plane disappeared March 8 with 239 people on board.
On Monday, investigators revised those last words to a common sign-off from Boeing 777: "Good night Malaysian three seven zero."
"We would like to confirm that the last conversation in the transcript between the air traffic controller and the cockpit is at 01:19 (Malaysian Time) and is 'Good night Malaysian three seven zero,' the Department of Civil Aviation said in a statement.
Authorities said they had launched a forensic investigation into whether the co-pilot, pilot or someone else made the final communication.
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