The missing MH370 flight may have stayed in the air for about four hours past the time it reached its last confirmed location.

According to a report in The Wall Street Journal (WSJ), aviation investigators and national security officials believed 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 engine.

The data sending is a part of its routine maintenance and monitoring programme.

Based on the plane’s speed, a total flight time of five hours after departing Kuala Lumpur means the plane 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.

WSJ reported that the United States counterterrorism officials are pursuing the possibility that a pilot or someone else on board the plane may have intentionally turned off the plane’s transponders to avoid radar detection and the diverted it toward an undisclosed location.

To date, United States national security officials have dismissed terrorism as the reason behind the tragedy but they have not completely ruled it out.

However, investigators reportedly are looking at the theory of the plane being diverted "with the intention of using it later for another purpose."

The engines' onboard monitoring system is provided by their manufacturer, Rolls Royce PLC, and it periodically sends data about engine health, operations and aircraft movements to facilities on the ground.

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.

The aircraft was scheduled to land at Beijing International Airport at 6.30am local Beijing time on March 8.

Subang Air Traffic Control reported that it lost contact at 2.40am (local Malaysia time) on the same day.

Malaysia Airlines is currently working with the authorities of other countries who have activated their Search and Rescue (SAR) team to locate the aircraft.