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The sky is one giant chessboard for air traffic controllers. In 314 control towers and navigation centers across the country, they hunker down in windowless rooms, staring at color-coded radar screens that show aircraft moving through thousands of square miles. Radio headsets crackle nonstop with pilots requesting course changes, asking for higher or lower altitudes, and, on a bad day, declaring emergencies. Each controller communicates with as many as 30 aircraft at a time, issuing commands that dictate each plane's movement.
A half century ago, flying was a much simpler affair. Pilots navigated by pointing their planes where they wanted to go, and it was up to the captain to steer clear of other aircraft in the sky. But with the surge in air travel following World War II, the Federal Aviation Administration stepped in to regulate commercial flight paths around major airports, and the responsibility for navigation shifted from pilots to air traffic controllers.
Remarkably, navigation technology has changed very little in the 50 years since its debut. Despite flying modern planes stacked with computers, pilots lack the capability to "see" the traffic around them and must rely on ground-based controllers for directions. The controllers, in turn, use a patchwork quilt of ground-based radar and radio transmitters to keep planes away from one another. The truth is, your car's GPS system has more precision than the air traffic control technology in use today.
Time Line
Early 1900s -- After the Wright brothers' first powered flight in 1903, aviation technology takes off. With the advent of airmail in 1918, the number of flights (and concerns about in-air collisions) soars. In 1921 the Post Office creates a system of rotating beacons, or transmitters, on towers to guide pilots.
Late 1920s -- The Air Commerce Act of 1926 ushers in airline regulation. In 1929 the city of St. Louis hires Archie League, the country's first air traffic controller. He uses two signal flags to direct planes. Red means hold; black-and-white means go.
1930s -- Airlines begin putting radios in planes; radio transmitters are installed at airports. Ground-to-air communication is now possible.
W. L. Smith flew in rain and fog to test new radio technology in 1929.
1940s -- World War II brings radar and the first women to air traffic control.
1950s and 1960s -- Congress creates the FAA to oversee air traffic. With new computer systems that can pinpoint a plane's position, speed, and altitude, controllers can now see air traffic in 3-D.
1970s and 1980s -- After Congress passes the Airline Deregulation Act of 1978, fares drop and air traffic increases. This leads to a strike by the air traffic controllers' union in
1981 -- On day three, President Reagan fires 11,000 strikers. The FAA hires new workers.
1990s -- Color displays replace monochrome screens in the control towers.
2001 -- On September 11, 2001, controllers can't prevent planes from crashing in New York, Washington, D.C., and Pennsylvania-but they do guide 4,500 planes carrying 350,000 passengers to safe landings (75 percent within the first hour). In the months afterward, air travel plummets and five airlines declare bankruptcy.
2002 to the present -- By 2003, sales are back up and planes are 90 percent full. The number of passengers reaches a record high in 2007 -- the same year the number of fully certified controllers (11,140) hits a 15-year low.
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