The FAA has contracted for four additional airports to have engineered materials arresting systems (EMAS) installed on runways that don’t have enough space for 1,000-foot-long runway safety areas. The arresting system uses crushable concrete to slow and stop an airplane that runs off the end of the runway. Fourteen U.S. airports have 18 of the systems installed, and construction of four systems is under way in San Diego; Charleston, W. Va.; Laredo, Texas; and Cordova, Alaska. Since 1999, EMAS has prevented injury and serious aircraft damage due to overruns three times, said authorities.