On January 201 1987, about 1228 central standard time, a U.S. Army Beech U21 A airplane Army 18061 and a Sachs Electric Company Piper PA-31-350 N60SE collided at 7,000 feet msl over the Lake City Army Ammunition Plant, Independence, Missouri, about 4 miles east of the eastern boundary of the Kansas City Terminal Control Area. The U-21 was level at 7,000 feet and en route to Fort Leavenworth, Kansas, in accordance with instrument flight rules. The PA-31 was climbing eastbound to an unknown cruise altitude, having departed the Kansas City Downtown Airport in accordance with visual flight rules, en route to Saint Louis, Missouri. The airplanes collided nearly head-on Inin daylight and visual meteorlogical conditions. Although both airplanes were equipped with operating mode-C transponders, the radar controllers in communication with the U-21 did not observe and were not alerted to the conflict. There traffic advisories were not provided. As a result of the accident, two pilots and one passenger aboard the U-21 and the pilot and two passengers abord the PA-31 were fatally injured. Both airplanes were destroyed.
We determined that the probable cause of the accident was the failure of the radar controllers to detect the conflict and to issue traffic advisories or a safety alert to the flightcrew of the J-21; deficiencies of the see and avoia concept as a primary means of collision avoidance and the lack of automated redundancy In the air control system to provide conflict detection between participating and nonparticipating aircraft.
As a result of the investigation, we issued recommendations to the Federal Aviation Administration, the National Business Aircraft Association and the Aircraft Owners and Pilots Association.
