VOA常速英语:How Can a Plane Be Lost?

With satellites crisscrossing the globe and GPS technology available at the touch of a button in everything from cars to cell phones, how did officials any sight of an airplane with 239 passengers on board?

Aviation safety consultant John McGraw says it’s easier than you think.

“People are under the impression that every airplane, even when it’s flying across the ocean, is observed on some kind of radar scope, with a human being looking at that scope," McGraw said. "And it's just not the case. Radars don't reach that far.”

But McGraw says there is a lot of technology inside the missing Malaysia Airlines Boeing 777 that helps pinpoint its location.

Systems in the jets automatically transmit altitude, weather conditions, position and speed of an aircraft to traffic control. There are also at least three ways the pilot can communicate with officials. If the plane is downed in the ocean, the flight data recorder, or “black box” sends out a sound that is detectable up to three kilometers away.

Former FAA accident investigator Michael Daniel says there are also global regulations.

“The airline has responsibility for what we call ‘flight following,’" said Daniel, managing director of aviation insight. "That’s an international standard and they are required to know where the airline is at all times.”

But in the case of Malaysia Airlines Flight 370, Daniel says the airline hasn’t provided a great deal of information.

“The standards may not have been followed,” he said.

Rescue crews continue a search to locate the jet and its "black box" to try to find out what went wrong.

After an Air France flight went missing in 2009, the U.S. National Transportation Safety Board called for continuously downloading segments of an aircraft’s flight data recorder information in case of emergencies.

“In the past they haven’t been able to justify installing that kind of equipment, because it’s expensive, and because there hadn’t been that many accidents where it would have come into play," said McGraw, the aircraft consultant. "This will certainly provide some additional motivation and there may be calls to do that.”

Militaries and navies from some 12 nations are working collaboratively in the search for the missing plane.

The search, which one aviation expert described as similar to looking for a "needle in a haystack," is being conducted with the help of more than 40 international ships and at least as many aircraft.

Operations are currently stretching across some 90,000 square kilometers of water, with international forces working in a grid pattern as not to overlap efforts.

Sid McGuirk, a professor of Air Traffic Management at Embry -Riddle Aeronautical University, said the search for the missing airliner is very difficult, calling it “one of the most bizarre sets of circumstances" that he’s ever seen in his career. He said the debris field, if the aircraft did impact on water, would be "significant".

Malaysia Airlines Flight 370 disappeared early Saturday on a flight from Kuala Lumpur to Beijing. Air traffic controllers from both Malaysia and Vietnam, near where the plane was last seen on radar, say they did not receive any messages from the cockpit alerting them that the plane may have been in trouble.

Experts say it is too early to speculate as to the cause of the suspected crash without the cockpit recorder, but say possible scenarios could include catastrophic failure, sabotage or foul play, or some sort of rare occurrence such as pilot incapacitation.