Advocatus Diaboli writes "Aviation investigators and national security officials believe the plane flew for a total of five hours based on data automatically downloaded and sent to the ground from the Boeing Co. 777's engines as part of a routine maintenance and monitoring program. As part of its maintenance agreements, Malaysia Airlines transmits its engine data live to Rolls-Royce for analysis. The system compiles data from inside the 777's two Trent 800 engines and transmits snapshots of performance, as well as the altitude and speed of the jet. Those snippets are compiled and transmitted in 30-minute increments, said one person familiar with the system." Update: 03/14 11:41 GMT by S : The WSJ has since updated its report to say the data was from the plane's satellite-communication system. However, Malaysian authorities have denied both scenarios, saying neither Boeing nor Rolls-Royce received data past 1:07am (the flight initially disappeared off radar at 1:30am).