3,000 Birds Disrupt Radar

Large flocks of migrating geese are suspected of causing a breakdown in the radar at the St. Louis air traffic control center last Wednesday morning. About 7 a.m., radar screens showed about 3,000 blips, which the system interpreted as 3,000 aircraft. The Airport Surveillance Radar model 9, or ASR-9, became overloaded and crashed, the St. Louis Post-Dispatch reported last week. Air traffic controllers in Kansas City took over the airspace for about 15 minutes, until St. Louis controllers were able to switch to a backup system. Similar flocks of birds are believed to have caused radar crashes in ASR-9 systems at Kansas City on Nov. 2 and at Boston on Oct. 10. ASR-9 comprises a primary antenna that detects when airplanes have entered the airspace, and a secondary radar that sends signals to the airplane transponder so it can identify the aircraft.