​​​Abstract On January 15, 1987, about 1252 mountain standard time, Skywest flight 1834, a Swearingen SA-226TC (METRO 11), and a Mooney M20 collided in fligh over Kearns, Utah, in visual meteorological conditions. The two pilots and six passengers aboard the METRO II and the two pilots aboard the Mooney were killed in the accident which occurred within the confines of the Salt Lake City airport radar service area.

​We determined that the probable cause of this accident was lack of navigational vigilance by the Mooney instructor pilot which led to the unauthorized intrusion into the Salt Lake City airport radar-service area. Contributing to the accident were the absence of a mode-C transponder on-the Mooney airplane and the limitations of the air traffic control system to provide collision protection under the circumstances of this accident.​