Technologies Aid Dulles International Airport Air Traffic Controllers

Those in the air traffic control tower at Dulles International (shown above) now can more easily detect potential runway conflicts thanks to Airport Surface Detection Equipment, Model X technology.

by Jessica Mulholland; photo by David Kidd / January 18, 2010
Photo by David Kidd. David Kidd

Ground traffic visibility has been a concern of air traffic control for years — which even includes airplanes on the tarmac. But that’s all about to change with the Automatic Dependent Surveillance-Broadcast (ADS-B) surveillance system technology, a transmission from which enables air traffic control (and ADS-B equipped aircraft) to know where other airplanes — and ground traffic — are. (It can also transmit other information, such as weather services, terrain maps and flight information services, altitude, the airplane’s registration number and vertical speed.)

Part of the technology necessary to do this — Airport Surface Detection Equipment, Model X (ASDE-X) — already has been operational in 26 U.S. airports, including Dulles International. Now, those in the air traffic control tower at Dulles International (shown above) can more easily detect potential runway conflicts. The data that ASDE-X uses comes from many sources, including ADS-B sensors.

There is an important difference between this new system and the old way of tracking planes in the air: Previously the nation's air traffic control system relied on less-rapidly updating radar technology; now, however, ADS-B technology enables use of precise location data from the global satellite network. With ADS-B, both pilots and controllers will see radar-like displays with highly accurate traffic data from satellites – displays that update in real time and don't degrade with distance or terrain. the data refreshed about every 20 seconds, meaning planes had to stay miles apart in the air and air traffic controllers never knew a plane’s exact location; now, however, the tracking data is instant, allowing planes to fly closer together and air traffic controllers to more easily track a plane’s location. The improved situational awareness will mean that pilots will be able to fly at safe distances from one another with less assistance from air traffic controllers. This new system also enables planes to fly more direct routes — they needn’t follow the old radio towers on the ground, which is said to save time and fuel. 

The most basic form of ADS-B will be mandatory at all U.S. airports by 2025. For more information about ADS-B and its implementation, visit