LONDON, March 15 -- An expert in military and civilian aircraft radar systems Saturday said evidences around the Malaysian missing plane showed the jet could have been tracked by satellite.

Professor David Stupples, professor in electronic engineering at City University in London, told Xinhua on Saturday that the communications with an Inmarsat satellite could reveal the route the missing flight took.

Stupples said it depended on how many of the planes electronic communications systems were shut down. "It is quite likely that the Inmarsat data is correct," he said. "It could be that they (people in control of the plane) switched stuff back on again for navigation purposes."

Professor Stupples is an expert in radar systems, and worked for many years with the Royal Signals Radar Establishment in Britain.

He said, "The information from radar systems, and the Malaysian air defense radar system is one of the best in the world was completed and handed over last year, would automatically have been tracking all aircraft in that area." he said.

"For it to have then suddenly disappeared and to have no secondary radar coming in would have meant that either this plane has met with a sudden and catastrophic event, or somebody has switched off all of the secondary systems, the transponder systems, and the communication systems, and then taken the aircraft down in height." He said.

Stupples said that the maximum range of the radar would have been 402 kilometers. If the aircraft was taken down to 6,000 meters it would then disappear from the radar because it would be over its horizon, he said.

He added, "I was speaking to a colleague of mine yesterday, who is a Boeing 777 captain, and he said the crew is not trained specifically on disabling all those systems because you have to go through quite a few circuit breakers to disable them."

They are normally set up on the ground by ground staff as the aircraft is prepared for flight, said Stupples.

He continued, "But if it is somebody external to the flight crew, who has somehow got access to the flight deck, then they would have to disable all of the flight systems, the communications systems onboard."

To land this plane, which weighs 200 tonnes, would need a runway of about 2,500 meters, and it would have to be a substantial runway, said Stupples.

If they are headed towards any landmass it is quite likely they are going to be picked up by primary radars, used for defense, said Stupples.

"If they are doing that, then their position will be known. Perhaps we cannot connect these positions with the missing airliner," he said.

Stupples added, "If I wanted to stay totally cloaked I would fly out over the Indian Ocean because there is hardly any radar there."

The plane could have been crashed into jungle, he added, where it would be hard to spot, but emergency beacons on the plane would continue to function and these could not be switched off by anybody on the plane.