[JonDuke]

Here's more from the WSJ article, without paywall:

For any WSJ subscribers.. US investigators say the engine data suggests the plane flew for 5 hours or 4 additional hours after the plane disappeared off radar. Engine data may also determine the flight path of the plane.

From the article:

"The engines' onboard monitoring system is provided by their manufacturer, Rolls-Royce RR.LN -1.71% PLC, and it periodically sends bursts of data about engine health, operations and aircraft movements to facilities on the ground.
Rolls-Royce couldn't immediately be reached for comment.

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. According to Rolls-Royce's website, the data is processed automatically "so that subtle changes in condition from one flight to another can be detected."

The engine data is being analyzed to help determine the flight path of the plane after the transponders stopped working. The jet was originally headed for China, and its last verified position was half way across the Gulf of Thailand.

A total flight time of five hours after departing Kuala Lumpur means the Boeing 777 could have continued for an additional distance of about 2,200 nautical miles, reaching points as far as the Indian Ocean, the border of Pakistan or even the Arabian Sea, based on the jet's cruising speed."

But the huge uncertainty about where the plane was headed, and why it apparently continued flying so long without working transponders, has raised theories among investigators that the aircraft may have been commandeered for a reason that appears unclear to U.S. authorities. Some of those theories have been laid out to national security officials and senior personnel from various U.S. agencies, according to one person familiar with the matter.

At one briefing, according to this person, officials were told *investigators are actively pursuing the notion that the plane was diverted "with the intention of using it later for another purpose." *

And an additional 4 hours, could bring it anywhere here (not the same map as posted here before)