Aircraft off the radar in this age puzzles experts

New York, March 13 (IANS) Can a modern aircraft with a plethora of advanced features just vanish into thin air?

Hard to believe but the disappearance of Malaysia Airlines Flight 370 is a puzzle that is growing even more complex.

�This is a very unusual event,� Sid McGuirk, an associate professor of air traffic management at Embry-Riddle Aeronautical University in Florida was quoted as saying.

�It is highly unusual for an aircraft at an altitude – which, at least according to the press, this aircraft was – to drop off the radar,� McGuirk added.

Radar facilities are based on land and each one has a range of about 300 km.

So passenger jets on transoceanic flights do go off the radar map for a period of time but that does not mean nobody is keeping tabs on them.

�The flight crews use combinations of high-frequency (HF) radio, satellite-based voice communication and text-data networks to report to Air Traffic Controller (ATC) the exact time, position and flight level when the crossing begins,� explained Emily McGee of the Flight Safety Foundation.

Commercial jets can also fall off the map briefly when they fly at low altitudes because radar relies on line-of-sight contact.

Mountains and other landforms can block the signals going to and from the closest radar stations, as can the curvature of the earth.

As a result, low-flying jets can be tough to track continuously, especially if their transponders are disabled – a fact that terrorists took advantage of on 9/11, said a report in LiveScience.