History of Flight
On August 6, 2023, about 1844 Pacific daylight time, a Bell 407 (N555AS) and a Sikorsky S-64 (N4037S) collided mid-air near Cabazon, California. Both helicopters were operating as public-use firefighting aircraft. The Bell 407 was tasked as a Helicopter Coordinator (HLCO) training flight, while the Sikorsky Skycrane was dispatched to support fire operations. The Skycrane received dispatch instructions about 15 minutes before departure.
Communications recordings from within the Skycrane began at 0:00 lapse time. At 01:18, the Bell 407 requested a bearing and distance to the fire from Hemet Base Victor Dispatch. ADS-B data showed the Bell 407 departed from HMT about 1834. The Skycrane crew discussed the Bell 407's role, and at 06:14, they made radio calls for departure. The Skycrane departed about 3 minutes after the Bell, maneuvering northeast.
At 11:23, the Bell 407 reported to ATGS being 8 miles west of the fire at 4,300 ft msl. ATGS cleared the Bell into the Fire Traffic Area (FTA) with a maximum altitude of 2,500 ft msl. The Bell initiated a steep descent and leveled off about 2,500 ft. At 12:08, the Skycrane SIC noted they tried to get clearance from ATGS. At 12:33, ATGS cleared the Skycrane into the FTA with the same altitude restriction. The Skycrane acknowledged at 12:45.
Subsequently, the Skycrane descended rapidly, passing through various altitudes and speeds. At 15:23, after a descent to about 2,450 ft, the right-side collective moved erratically, and the SIC asked, “oh …what was that?” The PIC asked if the Bell 407 struck the Skycrane, which the SIC confirmed. ADS-B data showed the helicopters converged. The Skycrew initiated a precautionary landing in a nearby field without further incident.
Surveillance footage showed the Bell 407 in level flight and the Skycrane descending at collision. The Bell's tail boom, main rotor, mast, and gearbox separated; the fuselage continued until terrain impact.
Personnel Information
The Skycrane PIC was hired by Siller Helicopters, Inc. in April 2017; last flight review April 27, 2023; last proficiency check May 3, 2023. The Skycrane SIC was hired in June 2023; last flight review April 27, 2023; last proficiency check June 24, 2023. The Bell 407 PIC was hired by Air Shasta Rotor & Wing Inc. in February 2018; last flight review April 27, 2023; last proficiency check June 20, 2023.
Wreckage and Impact Information
Postaccident examination of the Sikorsky revealed a 24-inch-wide cut on the right main landing gear tire, with a rubber transfer mark on the Bell 407's main rotor blade. The Bell 407 came to rest on a steep hillside about 1,050 ft from the last ADS-B data point. A post-crash fire consumed the fuselage. The debris path spanned about 950 ft by 550 ft. The main rotor blades, mast, and transmission were found about 285 ft northwest of the main wreckage; the tail cone and tail rotor assembly about 470 ft west. Examination of the Bell 407's airframe found no pre-impact anomalies. Flight control continuity from the transmission to the main rotor blades and to the tail rotor was established. The engine showed impact and thermal damage; testing of the engine control unit revealed no anomalies before the collision, with data consistent with an operational engine until a rotor droop event.
Communications
The National Wildlife Coordinating Group (NWCG) publication PMS 520 and PMS 505 provided guidance for airspace coordination in firefighting. The Fire Traffic Area (FTA) is a communication protocol, not a legal restriction. Key elements include an Initial Communication Ring (ICOM) at 12 nm and a No Communication Ring (NOCOM) at 7 nm. Pilots must receive clearance before crossing the NOCOM ring. CAL FIRE's Contract Aerial Resource Standards (CARS) further defined FTA procedures, stating pilots are responsible for maintaining visual separation and announcing intentions.
Flight Recorders
The Skycrane was equipped with an Appareo Vision 1000, which was recovered. The Bell 407 had a Go-Pro Camera, AIRS-400 Camera, and Garmin 650, but all were thermally damaged and unsalvageable.
Medical and Pathological Information
The Bell 407 pilot's autopsy determined cause of death as blunt trauma, manner accidental. Toxicological tests detected no drugs of abuse, but Cetirizine (an antihistamine) was found in blood and liver. Cetirizine may cause drowsiness; FAA advises a 48-hour waiting period before flying.
Organizational and Management Information
CAL FIRE's aerial division was tasked to the fire, with two S-2T tankers and a water-dropping helicopter already on scene under ATGS control. Air Shasta Rotor and Wing, Inc. operated the Bell 407 under an exclusive use contract as a public use aircraft for HLCO training. Siller Helicopters, Inc. operated the Skycrane under an exclusive use contract as a firefighting public use aircraft.