What happened
On the afternoon of the incident, two Douglas DC-4 airtankers, identified by registrations N96449 and N406WA, departed Hemet-Ryan Field in California. The aircraft were returning to their home base in Tucson, Arizona, following fire suppression assignments in Southern California.
While cruising at an altitude of roughly 9,500 feet, the crew of N96449 began capturing photographs of N406WA. To obtain better angles, the pilot of N96449 notified the other aircraft that they intended to reposition across the other side of the formation. After receiving clearance from the crew of N406WA, the aircraft began a 45-degree overtaking maneuver.
During this repositioning, the two planes suffered a mid-air collision due to insufficient vertical separation. The vertical fin of N964 and was struck by the right wing flap of N406WA, resulting in the loss of the former's rudder and fin. Subsequent impacts from the retardant tanks and the number two propeller of N406WA caused the tail section of N96449 to separate from the fuselage. Following the structural failure, N96449 entered a rapid descent, shedding debris before striking the ground in a nose-first impact that resulted in a post-crash fire. The captain and copilot were 2 fatalities.
Findings
The crew of N406WA declared an emergency with Palm Springs Approach Control shortly after the collision and successfully landed at Palm Springs Airport. The aircraft sustained significant damage, including impacts to its right wing flap, propeller blades, and fuselage, but remained airworthy for landing.