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.

The displays of the U.S.'s newer ATOP system Federal Aviation Administration

Besides just knowing where planes are with more-accurate and more-timely position reports, the benefits of modern systems are numerous: Flights are shortened by allowing more efficient routes, saving time for travelers, money for airlines and reducing the carbon footprint of airliners. And travelers get smoother flights because planes can fly closer together, allowing more to use the least-turbulent altitudes.

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.

"This is kind of a view into Next Gen," said Rick Day, senior vice president of operations for the FAA's air-traffic organization. "It's a total transformation from the controller's point of view."

The old oceanic control system whereby controllers kept track of planes with strips of paper. Federal Aviation Administration

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.

Controllers say the system is a huge improvement, but all the kinks haven't yet been worked out. ATOP gives them a radar-like picture of all planes in the section of oceanic air space they are responsible for, accurately showing position, direction, speed, assigned route and other information. Messages can be zapped back and forth with pilots. Any potential conflicts get automatically flagged to controllers as much as two hours before planes would get closer than separation standards allow. Problem flights are marked with flashing orange lines, and controllers have to take action to resolve conflicts before the lines go red 30 minutes before separation standards would be violated.

"Once the bugs got worked out, and most have been, we've been very happy with this," said Craig Troxclair, a controller at the FAA's oceanic traffic room near Oakland, Calif.—a facility that controls a huge swath of the Pacific Ocean, half-way around the world past Guam. "A lot of time used to be spent processing position reports on strips of paper. That took away from the service you could provide."

Indeed, controllers in Oakland used to have to keep track of planes with strips of paper, plot aircraft positions with grease pencils on maps and calculate flight paths using rulers and a plastic slide rule-like device called a "wiz wheel." And you can still find one or two around the Oakland facility.

Using ATOP, if a pilot requests an altitude or route change, the system loads the new information, based on the data transmission from the plane, calculates any possible conflicts and suggests responses from the controller automatically. If there aren't any problems with the request, approval can be sent with a couple of mouse clicks. And if any other flights are in the way of the requested new route, they get highlighted on the controller's screen in red.

"Previously if aircraft wanted to climb or reroute, it was a tedious process and controllers often didn't have time," said Dennis Addison, support manager for FAA's Oakland center. Now controllers can provide better routes and altitudes for flights. "It's really changed the way we do business," he said.

Controllers can allow airlines to design their own flight paths instead of using one of the 16 routes drawn up each day by controllers in the U.S. and Japan. (These are the routes that—based on winds, temperatures and other factors—controllers think will be best for that day.) That flexibility allows them to optimize each flight's route, based on the latest wind and temperature reports (the colder it is, the more efficient a jet engine is).

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.

Write to Scott McCartney at middleseat@wsj.com