Incident Overview
At 1640 CDT, a Cessna 172, registration N5279R (79R), reported 7 miles southeast for landing. The aircraft was transporting blood for the Red Cross. Meanwhile, another Cessna 172, N6376F (76F), was practicing touch-and-go landings with a student and a certified flight instructor (CFI).
Air Traffic Control Communications
The tower controller observed a target in that vicinity using D-Brite radar and instructed 79R to enter a left downwind for Runway 12 and report 2 miles southeast. At 1643, the controller was relieved by a developmental controller (DC) and a full performance controller (FPC). During the briefing, the departing controller informed the relief team of the positions of aircraft in the traffic pattern and that 79R was inbound from the southeast, but did not show them its position on radar.
At 1644:55, 79R made a radio call stating the aircraft was "practically straight east of the airport." 79R was told again to report on downwind but never did so. Both controllers were working several aircraft; they neither sighted 79R nor used radar to locate it.
Collision Sequence
At 1647:06, 79R called turning base for Runway 12. At that time, 79R was tracking inside the flight path of 76F, as 76F was in a left turn to final approach for Runway 14. Approximately 25 seconds later, the two aircraft converged, collided, and then crashed to the ground.