What happened
Two aircraft were approaching the airport from the south-southwest, flying on headings assigned by air traffic control. At the time of the incident, neither aircraft had been assigned a specific altitude. Just prior to the collision, approach control instructed the Beechcraft C-402B to fly heading 360 to follow other traffic and asked for its current altitude. When the pilot responded that he was at 2,300 feet, the controller immediately warned him that there was a Cherokee aircraft right next to him. The collision occurred approximately five seconds after this warning.
Following the impact, the Piper PA-28 made a forced landing in a retention pond. The Beechcraft C-402B managed to land without further incident. Of the eight air traffic control personnel on duty at the TRACON, only three were assigned control positions; the others were either on break or out for dinner. The controller involved had nine aircraft under his control at the time of the accident.
The investigation
Both aircraft were within the controller's airspace and had been assigned transponder codes. They had been radar identified and given headings for sequencing purposes. The only traffic advisory issued to either aircraft regarding the other was the imminent collision warning delivered to the C-402B pilot moments before impact.
Findings
The accident occurred due to a failure in air traffic control separation during the approach phase. Despite having radar identification and assigned headings for sequencing, the controller did not detect the conflict until it was too late. The limited staffing at the TRACON may have contributed to the controller's workload, as he was managing nine aircraft with only three controllers on duty.