What happened
On November 1, 2013, a search and rescue operation for a 12-foot boat that had been missing for two days resulted in a mid-air collision. During the mission, a Hercules aircraft collided with a Bell AH-1 Cobra helicopter belonging to the US Marine Corps. The impact caused both aircraft to crash into the ocean, approximately 24 km away from San Clemente Island.
Following the collision, all occupants on both aircraft were reported missing. Despite the ongoing efforts to locate the wreckage, the search and rescue operations were officially terminated on November 1, 2013, after no evidence of the Hercules or the Bell AH-1 Cobra could be located.
Findings
Investigations into the incident suggested that the Bell AH-1 Cobra was participating in a military exercise within a designated training zone at the time of the accident. A significant contributing factor was that the helicopter's anti-collision lights and IFF transponder were not activated, which likely hindered the ability of the other aircraft to detect its presence.