History of Flight
On July 23, 2012, at approximately 1745 Pacific daylight time, an Aero Commander 500 S (N535SA) experienced a complete loss of power in both engines during an air-attack coordination flight for aerial fire suppression near Elko, Nevada. The pilot executed an off-airport forced landing on Nevada State Highway 228. Neither the pilot nor the onboard Air Tactical Group Supervisor (ATGS) was injured. The aircraft was substantially damaged.
The flight departed Elko International Airport (EKO) at about 1315 and proceeded to a fire located roughly 15 minutes east of EKO. At 1319, the pilot reported having 4 hours 30 minutes of fuel onboard. The aircraft loitered near the fire as the ATGS coordinated air attacks. At approximately 1730, the pilot advised the ATGS of the need to return to EKO. Shortly after turning towards EKO, the engines began surging and then ceased producing power. The pilot chose to land on a two-lane highway due to lower vehicular traffic compared to a nearby four-lane road. The flight radioed the Interagency Dispatch Center (IDC) at 1744 about the planned off-airport landing, and at 1751 reported a safe landing with no injuries but aircraft damage.
Personnel
The pilot held Airline Transport Pilot and other certificates, with approximately 16,800 total flight hours including 1,500 hours in the accident make and model. He held a valid FAA second-class medical certificate issued in April 2012 and completed a flight review in May 2012. He was certified by the Department of the Interior Office of Aviation Services for the mission. The pilot was employed by Spur Aviation Services and completed annual fire-mission training on May 23, 2012. He had flown 121 hours in the prior 30 days and 22 hours in the prior 10 days.
The ATGS was a Bureau of Land Management employee, qualified per the Interagency Aerial Supervision Guide (IASG). The IASG indicated the ATGS should assist the pilot as requested with crew duties. The ATGS had completed Crew Resource Management training in April 2007. It was not determined whether the ATGS held any pilot certificates.
Aircraft
The 1972-model Aero Commander 500 S was equipped with two Lycoming TIO-540 series piston engines. Total time in service was 6,443 hours; each engine had 1,323 hours since overhaul. The aircraft was maintained under an FAA-approved inspection program, with the most recent inspection completed on July 16, 2012. It was certificated per Department of the Interior policies and met the Bureau of Land Management exclusive-use contract requirements.
Weather
Recorded weather at Elko between 1256 and 1656 included strong winds, gusts, heavy rain, and thunderstorms. During the return leg, winds were gusting to about 20 mph from the north-northwest, providing a headwind.
Wreckage
The aircraft landed on a straight, 2,300-foot-long section of two-lane highway about 6 miles southeast of Elko, at an elevation of approximately 5,300 feet. The outboard leading edges of both wings struck highway signs, causing substantial damage. The aircraft was moved clear of the road by about 1830.
Examination two days later found the fuel gauge indicating zero. Approximately three-quarters of a gallon of fuel was drained from the tanks, consistent with fuel exhaustion. No fuel leaks were detected, and after temporary repairs, the aircraft was flown successfully to Elko and later to Oregon without any anomalies.
Fuel Considerations
The aircraft’s usable fuel capacity was 156 gallons distributed across five interconnected tanks. The fuel gauge, limited to a maximum indication of 135 gallons, had last been calibrated in May 2011. Spur Aviation Services’ operations manual required the pilot to be present during fueling and to verify the amount serviced. The pilot reported being present, but fixed-base operator personnel stated he left before fueling was completed. The ATGS assisted with refueling, contrary to the Bureau of Land Management contract, which prohibited BLM personnel from involvement except in emergencies.
The pilot’s company training cited an overall fuel burn of 30 gallons per hour (gph), while manufacturer data indicated 17 to 31 gph depending on power settings. The pilot reported setting power for 30 gph and letting airspeed vary. The aircraft had a cockpit fuel flow gauge, but its accuracy was not determined.
The pilot departed the fire area at about 1730, 4 hours 15 minutes after takeoff, approximately 14 minutes before fuel exhaustion. He estimated 25 to 35 gallons remaining based on time and fuel flow, but the gauge read zero. Previous flights in the week before the accident ranged from 24.6 to 36.6 gph calculated burn, but actual fill levels could not be verified. The most recent refueling added 80.4 gallons at tachometer time 1,279.5; the accident occurred at tach 1,284.0. Calculated average burn ranged from 30.0 to 34.7 gph depending on initial fuel quantity. No company-specific reserve fuel policy existed; the pilot relied on Part 135 requirements of a 30-minute reserve (15 gallons at 30 gph).
Crew Coordination
The IASG required a mission briefing covering fuel aspects, but the pilot and ATGS did not conduct such a briefing. They also did not discuss emergency roles and responsibilities as required. Neither the Department of the Interior nor the Bureau of Land Management documents mandated a pre-determined minimum fuel value for departure or periodic fuel state communication.
Other Information
The Pilot’s Handbook of Aeronautical Knowledge and FAA Risk Management Handbook describe situational awareness and risk management concepts, which were referenced in the investigation.