What happened
While engaged in an aerial firefighting mission for the California Department of Forestry, two Grumman TS-2A aircraft, identified as N442DF and N450DF, collided in mid-air. At the time of the incident, the aircraft were operating in a holding pattern near a wildfire. The Air Tactical Group Supervisor was orbiting at 1,000 feet, while the tankers were maintaining a counterclockwise orbit at approximately 3,000 feet mean sea level.
Investigation into the sequence of events revealed that N442DF was maneuvering to follow another aircraft in the sequence. The pilot of N442DF had extended the flaps, indicating the aircraft was configured for a retardant drop. During this maneuver, the aircraft swung wide from the established orbit. Simultaneously, N450DF was flying a direct path toward the fire center, a trajectory that had not been observed from other tankers earlier that day.
The collision occurred at an altitude of approximately 2,500 feet. The right engine, propeller, and cockpit area of N442DF struck the empennage of N450DF, causing the tail section of the second aircraft to separate. It is believed that a nearby ridgeline may have obstructed the pilots' views of one another immediately before the impact.
Findings
Several contributing factors were identified following the accident. There was a notable lack of standardized operating procedures within the California Department of Forestry, as the agency lacked a formal manual for managing holding orbits or established entry points. While training materials suggested that incoming tankers should establish radio contact with the Air Tactical Group Supervisor before entering the orbit, there were no codified rules for the direction of entry.
The absence of standardized procedures for entering the holding orbit was a primary factor. Furthermore, the Air Tactical Group Supervisor's logs did not record the arrival of N450DF, and other pilots on the radio frequency did not recall the aircraft checking in. The lack of a uniform protocol allowed the aircraft to enter the pattern in a manner that led to the fatal mid-air encounter.