Heathrow International uses radar for runway safety.
On July 25, 2000, an Air France Concorde ran over a piece of titanium debris while taking off from Charles de Gaulle International Airport. Minutes later 113 people perished in a ball of fire.
Most airports rely on visual inspections to keep runways clear of foreign objects and prevent what happened in France, but Heathrow International Airport, the world's busiest, has now installed a permanent dual radar system called the Tarsier, which scans 3,658 meters of runway in search of junk 24 hours a day.
The Tarsier uses networked high-frequency, high-resolution radar and integrated digital signal processing to pinpoint anything from a pigeon to a cellophane sandwich wrapper (PDF).
Foreign object damage, or "FOD," is responsible for $60 million worth of damage a year, an average of $15,000 per aircraft for each major airline in the U.S. alone, according to the FAA (PDF).
FOD can be caused by wildlife, stray tools, pieces of rubber, or any other imaginable debris strewn across a runway. A rock sucked into a jet engine can "shred turbine blades in a matter of seconds," the FAA says.
The system allows automated runway inspections around the clock, rain or shine, and with no disruption to airport traffic, according to the manufacturer, QinetiQ. It can be further enhanced with cameras that allow remote visual confirmation of debris.
The smallest item detected to date is a 10-millimeter metal fitting in an area the size of 30 football fields, the company says. Once an object is found, Tarsier reports its latitude and longitude to within 3 meters via GPS.
The system has also been tested in Dubai, Amsterdam, Vancouver, and Sydney, according to QinetiQ. The U.S. Air Force has used the equipment as well.
"I believe that this system will become the international standard in the next 5 to 10 years and other airports will follow suit," said Brett Patterson of the Vancouver International Airport Authority.