History of Flight
On January 31, 2011, about 1115 mountain standard time, a McDonnell-Douglas 369FF helicopter, registration N530RL, was substantially damaged while attempting a pinnacle landing on Waterman Peak, approximately 30 miles west-northwest of Tucson, Arizona. The public-use flight, operated by the Pima County Sheriff's Department (PCSD), was supporting the Pima County Wireless Integrated Network (PCWIN) communications development project. The pilot received fatal injuries, two passengers suffered serious injuries, and one passenger sustained minor injuries. Visual meteorological conditions prevailed; no flight plan was filed.
The flight's purpose was to enable PCWIN personnel to conduct a site survey for a planned communications repeater tower installation. The helicopter departed Tucson International Airport (TUS) about 1050 with the PCSD pilot in the left front seat, two Pima County employees in the right front and rear seats, and a private contractor in the left rear seat. Initially, the flight communicated with and was tracked by TUS local and TRACON air traffic control (ATC) facilities, but communications were intentionally terminated once the helicopter was well clear of TUS airspace.
The helicopter orbited Waterman Peak counterclockwise approximately twice for reconnaissance before the landing attempt. The pilot selected a landing zone (LZ) on a relatively level area of a pinnacle on the northeast side of the mountain, approaching from the southeast. Passengers reported feeling a "bump" during the landing attempt; the helicopter then either bounced or the pilot lifted off again, the nose pitched down, and the helicopter began to spin to the right. A ground-based witness located about 1,000 feet west of and below the LZ observed the helicopter complete about four or five rotations before it disappeared from his view. The main rotor blades struck a rock outcrop northeast of the LZ, after which the helicopter tumbled and slid about 120 feet down a shallow canyon on the northeast face of the peak, stopping against rocks and scrub vegetation. Two passengers used mobile phones to call 911. Multiple agencies participated in rescue and recovery efforts.
Personnel Information
FAA records indicated the pilot held a commercial pilot certificate with rotorcraft-helicopter and instrument-helicopter ratings, and a private pilot certificate with airplane single- and multi-engine land ratings. His personal flight log showed approximately 11,500 total flight hours, predominantly in helicopters. His first flight in the accident helicopter make and model was in August 2008, accumulating about 186 hours total. In January 2011, excluding the accident flight, he logged 6 flights totaling 7.5 hours in that equipment. His most recent FAA second-class medical certificate was issued in February 2010.
According to PCSD records, the pilot joined the department in November 2008 and had about 30 years of helicopter experience with the Arizona Department of Public Safety and the Maricopa County Sheriff's Department. He had satisfactorily completed training and demonstrations for confined area, slope, and pinnacle landings.
The Pima County Office of the Medical Examiner autopsy listed cause of death as "multiple blunt force injuries." Forensic toxicology examinations detected no carbon monoxide, cyanide, ethanol, or other screened drugs.
Aircraft Information
The helicopter was manufactured new in 1985 as a Hughes 369E, serial number 0128E, and converted to a McDonnell Douglas 369FF, serial number 0602FF, in September 1998. It was equipped with an Allison (Rolls-Royce) 250-C30 turbine engine. Pima County registered the helicopter in 2008. The aircraft featured left-seat command with dual controls, but the right-seat pedals were not installed for the accident flight.
The most recent 100-hour and annual maintenance inspections were completed on April 13, 2010, at a total time (TT) of 3,626.9 hours. At the accident, TT was 3,740.3 hours. Maintenance records indicated compliance with applicable Service Bulletins and Airworthiness Directives. Weight and balance calculations showed the helicopter within its certificated envelope. Fueling records confirmed proper fuel and sufficient quantity.
Meteorological Information
At the time of the accident, two low pressure systems were to the east and a high pressure system to the northwest. No defined surface boundaries were in the accident site vicinity. Station models indicated a general westerly wind at about 10 knots, varying from west-southwest to west-northwest, scattered clouds, temperatures around 10-14°C, and dew points about 0-4°C. A National Weather Service Convective Outlook forecast issued about two hours before the accident included a risk of general air mass thunderstorms over eastern Arizona.
The closest weather station, 19 miles southeast at 2,417 feet elevation, reported about 30 minutes before the accident: wind from 090 degrees at 11 knots gusting to 16 knots, visibility 10 miles, few clouds between 5,500 and 7,500 feet. Another station 30 miles southeast at 2,643 feet reported about 30 minutes before: wind from 300 degrees at 9 knots gusting to 16 knots, visibility 10 miles, ceiling broke 7,000 feet, temperature 12°C, dew point 1°C. One hour later, that station observed gusts to 24 knots.
Satellite imagery showed the accident site under a band of clouds with embedded cumulus congestus in stratocumulus. Witnesses reported the mountain visible below an overcast and some rain. The closest ground-based witness, several hundred feet below, stated it was "windy," but local topography differed from the LZ. No passengers reported wind. An AIRMET for moderate turbulence below 15,000 feet and another for moderate icing between the freezing level and 18,000 feet were current. The pilot's weather briefing could not be determined; Lockheed Martin reported no briefing services provided in the 24 hours prior.
Wreckage and Impact Information
Main wreckage, comprising fuselage and tail boom, came to rest in a canyon below a pinnacle on Waterman Peak at approximately 3,595 feet elevation. Rotor blade fragments and fuselage/landing gear components were distributed above and below the main wreckage. The fuselage lay on its left side, oriented transversely across the canyon. The front canopy and frame, and the aft 5 feet of the tail boom, were fracture-separated. Main and tail rotor blade fragments were primarily on the pinnacle. The rock outcrop at the canyon top bore main rotor blade fragments and scars. A 3-foot diameter shrub near the southeast end of the LZ was uprooted, but not directly associated with the accident sequence.
Wreckage examination occurred in situ on February 1 and after recovery on February 3-4. All components were accounted for. The five main rotor blades were highly fragmented with scoring consistent with strikes under power. Both tail rotor blades were missing about one-third of their span; remaining root sections showed twisting, splitting, and chordwise scoring. Tail rotor fragments found in a debris field about 250 feet long bore chordwise scoring, consistent with strikes under power. The pilot-side anti-torque pedals were fracture-separated; metallurgical examination showed no pre-existing defects, fractures were impact-related.
The rotor transmission and gearboxes were intact, free to rotate, with proper oil levels and clean chip detectors. Tail rotor drive shaft damage was impact-related. Flight control continuity was validated from cockpit to endpoints; all damage and discontinuities were consistent with impact. The engine, slightly damaged, was removed and successfully met specification power in a test fixture on February 7. All damage patterns indicated a low-speed impact in horizontal and vertical planes, followed by tumbling down the canyon with engine driving rotors. No evidence of pre-existing mechanical defects or malfunctions was found. A passenger's video recording of portions of the flight contained no imagery of the approach or accident.
Organizational and Management Information
The helicopter was operated by the PCSD Tactical Air Support Unit (TASU), primarily supporting law enforcement patrols and secondarily prisoner transport, with other missions as required. The TASU fleet included four fixed-wing aircraft and one rotary-wing aircraft (the accident helicopter). Six pilots were in the unit, including the accident pilot and the Air Unit Supervisor. Two pilots were mission-qualified on rotary-wing aircraft. The helicopter, acquired under the Urban Area Security Initiative, was primarily used for training at the time of the accident.
TASU procedures included pre-coordination with ATC for missions within Tucson TRACON airspace, using pre-assigned transponder codes and call signs. Most flights remained in communication with ATC unless geography or radio coverage prevented it. Operational minima were dictated by FAR Part 91; pilots were to evaluate conditions if winds were constant above 30 knots or if gust spread exceeded 15 knots. Twice-yearly operational and safety stand-downs occurred; annual risk assessments focused on workplace hazards, not flight safety. No formal risk assessments were mandated for individual missions; pilots assessed risks individually. The Air Unit Supervisor could approve or disapprove flights but typically did not for routine missions.
TASU pilots worked 4-6 month rotations of night or day shifts. Each crew consisted of a pilot and a tactical flight deputy (non-pilot equipment operator). No mandatory flight or duty time limits existed, but recommended values were 6-8 hours flight and 14 hours duty per day. The accident pilot's TASU missions included tactical insertions at non-mountainous sites, slope and pinnacle landing practice, and hover practice. He had long line and Bambi bucket experience, though PCSD did not conduct those operations.
The flight was requested via email to the TASU Air Unit Supervisor by the PCWIN responsible individual. The supervisor instructed the accident pilot to coordinate and treat it as a practice/training flight. A few days prior, on January 20, 2011, the pilot conducted a solo 1.7-hour reconnoitering flight; further details could not be determined.