Satellite Technology, the better choice

Found an interesting article about building a better air traffic control system with the help of satellite technology, and thought I would share it with you.

When Air France Flight 447 crashed in the Atlantic Ocean in June, seven hours elapsed before air-traffic controllers realized it was missing, delaying search and rescue efforts and bewildering air travelers over how a jumbo jet could be lost in an age when even simple cellphones can pinpoint positions.

Could it happen in the U.S. and other parts of the world? Thanks to a relatively new breed of air-traffic-control systems, that isn't likely. Air-traffic controllers in the U.S., Europe, Canada, Australia and New Zealand, who control most of the air traffic across oceans, now have modern satellite-based systems that include frequent automatic position reporting from airplanes and email-like communications between pilots and controllers.

What's happened in recent years over oceans offers a glimpse of what governments and airlines hope will happen over land—a "Next Generation" system that will be a vast improvement over the ground-based radar and radio communications system in place for the past 50 years.

The Federal Aviation Administration's "NextGen" development program for the continental U.S. has a history of delays and failures. But it is now on track, according to government and industry groups, to produce in the next 10 years or so an air-traffic-control system with lots more capacity. With satellite-based data links instead of radar, which is somewhat slow and not precisely accurate, jets will be able to safely travel closer together, reducing delays. Faster communications over data links will allow controllers to handle more airplanes at one time. And with better computer systems that can predict conflicts far in advance, planes will get to pick their best route rather than be restricted to the set paths in the sky today. Systems to handle busy skies over land will be different from the oceanic system, but built with the same functions, communications and data links.

The U.S. system, called Advanced Technology and Oceanic Procedures, or ATOP, was adapted by Lockheed Martin Corp. from a system developed in New Zealand (Australia's system was the other finalist). So far, ATOP has saved airlines 330,000 flying miles per year—as far as flying to the moon and half-way back—and nearly 10 million gallons of fuel.

The system has been in use in the U.S. for four years. Data come from multiple sources on board aircraft, in case one fails, and multiple computers run together on the ground to provide backup. Planes report every 14 minutes, though controllers can change that to more frequent reporting, if necessary. If a position report is six minutes overdue, alarms go off. And the system automatically warns controllers if planes stray off course.

Controlling planes over oceans presents all kinds of challenges because aircraft are out of normal radio and radar range. For decades, controllers relied on position reports over high-frequency radio every hour or so, competing for air time with fishing vessels and all kinds of other traffic.

Because of the inaccuracies and time between reports, planes were spaced far apart—often about 100 miles—to ensure safety. That added to delays since flights had to wait for space in the stream of planes and made it difficult for lots of flights to get on ideal tracks for winds, slowing flights and increasing fuel burn. It also made it hard to change altitudes when the ride got bumpy. Now, with more-accurate and timely position reporting, separation between airplanes can be reduced to as little as 30 miles over oceans. (Over land, planes are kept at least five miles behind one another, but that may well be reduced when satellite-based navigation replaces radar.)

Not all planes across oceans have data-link capabilities, and high-frequency radio is still used with some flights and as a backup with others. Many aircraft also have satellite phones that controllers can call. And some nations, notably Brazil and Senegal, which were handling Air France Flight 447, don't yet have modern oceanic air-traffic-control systems. The Airbus A330 jet with 228 people aboard crashed on June 1 about 930 miles off the coast of Brazil. Senegal never took control of the jet from Brazil, and it wasn't until seven hours later that controllers in Madrid and Brest, France, raised an alarm, investigators said.

For the full article: Visit The Wall Street Journal