Several sources, here's one: http://www.washingtonpost.com/local/trafficandcommuting/malaysia-airlines-flight-recorder-beacons-send-signal-for-30-days-before-ba

Several sources, here's one: http://www.washingtonpost.com/local/trafficandcommuting/malaysia-airlines-flight-recorder-beacons-send-signal-for-30-days-before-batteries-die/2014/03/11/1d1cb3d8-a8a2-11e3-b61e-8051b8b52d06_story.html http://www.washingtonpost.com/local/trafficandcommuting/mala... Yeah - sorry I should have clarified voice recorder not the flight data recorder. Will edit.