Elko, NV, USA
N535SA
AERO COMMANDER 500 S
The flight mission was to provide airborne coordination for an aerial fire suppression effort. The pilot was a company employee, and the other crewmember, who was not functioning as a pilot, was an employee of the Bureau of Land Management (BLM). Although the pilot was required by the company to remain present for the duration of the airplane fueling before the flight, he did not do so. A design peculiarity of the fuel quantity system prevented in-cockpit determination of the actual fuel quantity once the fuel level rose above a value that was 21 gallons below the actual maximum capacity. Only a visual inspection of the tank would enable determination of the actual fuel quantity above that level or whether the tank was completely full. The pilot reported that he began the flight with full fuel, but there was no evidence that he visually checked the fuel level. Therefore, it is possible that the flight began with as much as 21 gallons less than the pilot believed. After takeoff, the pilot radioed to his dispatch center that he had 4 hours 30 minutes of fuel on board. Company rules and the exclusive-use contract with the BLM required the pilot to comply with Federal Aviation Administration regulations that precluded departure without a 30-minute fuel reserve. The fire was located about 15 minutes (still air) flight time from the base airport, but the return flight would be subject to a headwind of about 10 knots. Exclusive of the 30-minute fuel reserve requirement for the beginning of the flight, there were no mission-specific or other factors that dictated the pilot's turnback time. About 4 hours 15 minutes after departure, with the airplane fuel quantity gauge indicating 0 gallons of fuel, the pilot turned back to base. Shortly thereafter, both engines lost power due to fuel exhaustion, and the pilot conducted a forced off-airport landing. The company's and BLM's guidance differed in several aspects regarding the flight planning, briefing, and communication requirements. Due in part to those differences, the two crewmembers did not conduct any preflight briefing, or any in-flight communications, regarding fuel status. Neither of the two was required to, and they did not, establish a minimum fuel value which, when reached, would require them to depart the operating area and return to base. The fuel quantity system had been calibrated about 14 months before the accident, and postaccident examination of the airplane did not reveal any mechanical problems that would have resulted in premature fuel exhaustion. The pilot reported that he relied on his time and fuel consumption calculations instead of the cockpit fuel quantity gauge to determine the fuel remaining and his turnback time. His calculations were based on starting the flight with full fuel tanks, and a nominal flight-planning fuel consumption rate, neither of which could be verified after the accident. Postaccident calculated fuel consumption rates for the flight were in the same range as both recent historical data from the accident airplane and the manufacturer's published values. Although the pilot could have used the fuel gauge in addition to his calculations to determine the remaining fuel, he chose not to. The more conservative risk management approach would have been to turn back to base when the fuel gauge reached the minimum value necessary to complete the flight safely. In addition, neither of the crewmembers explicitly determined and communicated a minimum fuel quantity value that mandated a return to base, and none of their guidance explicitly recommended or required them to do so.
HISTORY OF FLIGHT On July 23, 2012, about 1745 Pacific daylight time, an Aero Commander 500 S, N535SA, was substantially damaged during an off-airport forced landing near Elko, Nevada, due to the complete loss of power in both engines. Neither the pilot nor the Air Tactical Group Supervisor (ATGS) was injured. The public-use flight was performing an air-attack coordination mission for aerial fire suppression activity. The airplane was owned by Spur Aviation Services of Twin Falls, Idaho, and was being operated on an exclusive use contract by the United States Department of the Interior, Bureau of Land Management (DOI/BLM). No Federal Aviation Administration (FAA) flight plan was filed for the flight. A Fire Traffic Area was established and aviation support was controlled by the ATGS. The flight departed Elko International airport (EKO), Elko, about 1315, and flew to the vicinity of the fire, located about 15 minutes east of EKO. Interagency Dispatch Center (IDC) records indicated that at 1319, the pilot radioed that they were airborne, with 4 hours 30 minutes of fuel on board. The airplane loitered in the vicinity of the fire to enable the ATGS to coordinate the air attacks. About 1730, the pilot notified the ATGS that they had to depart the fire locale for a return to EKO, and shortly thereafter, the airplane turned on course for EKO. While en route back to EKO, at a point that the ATGS estimated was 4 to 5 minutes away from EKO, the engines started "surging," and soon thereafter, the engines ceased developing power. The pilot decided that due to distance and terrain considerations, he would land off-airport instead of attempting to return to EKO. Although the airplane was in the vicinity of a four-lane highway, the pilot opted to land on a two-lane highway due to significantly less vehicular traffic on that highway. About 1744, the flight radioed IDC that the pilot was planning to conduct an off-airport landing. About 1751, the flight radioed that they had landed on Nevada State Highway 228, and that the occupants were uninjured, but that the airplane was damaged. PERSONNEL INFORMATION Pilot The pilot held multiple pilot certificates (including Airline Transport Pilot) and ratings, and was appropriately certificated and rated for the accident airplane make and model. The pilot's records indicated that he had a total flight experience of about 16,800 hours, including about 1,500 hours in the accident airplane make and model. His most recent FAA second-class medical certificate was issued in April 2012, and his most recent flight review was completed in May 2012. In addition, he was properly certificated ("carded") by the DOI Office of Aviation Services (OAS) for the mission. The pilot was employed by Spur Aviation Services. He completed his company-provided fire-mission flight and ground training, which is conducted annually prior to the each fire season, on May 23, 2012. His ground training session was 8 classroom hours, and included company-created modules regarding the airplane fuel system, fuel handling and management, and flight planning. The pilot had been stationed at Elko since July 9, 2012. Since that time, he operated within the applicable crew day and flight hour requirements. His records indicated that he had flown the accident airplane make and model 121 hours in the previous 30 days, and 22 hours in the previous 10 days. The pilot stated that, on the day of the accident, he began his day with a good breakfast, and that he was well rested. Air Tactical Group Supervisor (ATGS) The ATGS was employed by the BLM. The Interagency Aerial Supervision Guide (IASG) was a primary guidance document for the conduct of BLM fire suppression operations, and the ATGS was qualified and current to conduct fire suppression missions in accordance with the IASG. According to the then-current IASG, in addition to aerial supervision of the fire suppression efforts, the ATGS was to "assist the pilot as requested with crew duties." Although not required for ATGS certification, the Crew Resource Management (CRM) course was cited in the IASG as a training opportunity that "should be considered prior to initial certification or as a supplemental or refresher training (for) individuals currently certified as air tactical group supervisors." The ATGS completed the CRM course in April 2007. It was not determined whether the ATGS had obtained any pilot training, or held any pilot certificates. AIRCRAFT INFORMATION FAA information indicated that the airplane was manufactured in 1972, and was equipped with two Lycoming TIO-540 series piston engines. At the time of the accident, the airplane had accumulated a total time in service (TT) of 6,443 hours, and each engine had accumulated a TT since overhaul of 1,323 hours. The airplane was maintained under an FAA-approved inspection program, and its most recent inspection was completed on July 16, 2012. The airplane was certificated ("carded") in accordance with DOI/OAS policies and procedures, and met all requirements of the applicable BLM exclusive- +use contract. METEOROLOGICAL INFORMATION Recorded weather information at EKO indicated that between 1256 and 1656 inclusive, there was significant weather activity. That activity included strong winds, stronger gusts, heavy rain, and thunderstorms. During the attempted flight leg from the fire area back to EKO, the winds were recorded as gusting to about 20 mph from the north-northwest; that wind direction presented a headwind for the returning airplane. WRECKAGE AND IMPACT INFORMATION The airplane landed on a straight section of two-lane highway that was about 2,300 feet long, and located about 6 miles southeast of EKO. The landing site elevation was about 5,300 feet above mean sea level. IDC records indicated that the airplane was pushed clear of the road about 1830. Personnel from the FAA, BLM,.032 and DOI examined the airplane 2 days after the event. The airplane sustained substantial damage to the outboard leading edges of the left and right wings due to impacts with highway signs located on each side of the road. Electrical power was applied to the airplane, and the fuel quantity gauge registered "0," which indicated that the fuel tanks were devoid of usable fuel. Investigators opened the fuel sump drain line to determine the amount of fuel remaining in the fuel tanks. About 3/4 gallon of fuel was drained from the airplane, which was consistent with the fuel quantity gauge indication. The airplane was examined to determine if the lack of fuel was due to a fuel leak. There was no evidence of discoloration or residue on the airplane that would indicate a fuel leak. The airplane was refueled, and a fuel leak check was conducted. Again, no evidence of a fuel leak was observed. Temporary wing repairs were accomplished on the airplane, and it was flown successfully from the accident site to EKO, and subsequently to Oregon for permanent repairs. Both flights were uneventful, with no indications of any fuel- or engine-related abnormalities. ADDITIONAL INFORMATION Airplane Fuel System The airplane had a usable fuel capacity of 156 gallons, distributed in five interconnected tanks. The fuel quantity indication system utilized a mechanical float located in the main fuel cell. The fuel quantity gauge indication was limited to 135 gallons, with index marks in 10 gallon increments from 0 to 120 gallons. The next index mark was also the uppermost, and indicated 135 gallons. Since the indicated quantity could not exceed 135 gallons, the only way to determine whether the actual fuel quantity was above that level or full was to open the wing refueling port, and visually check the fuel quantity. Maintenance records indicated that the fuel quantity indication system was last calibrated in May 2011, about 14 months prior to the accident. Per the airplane maintenance manual, the "Indicator reading shall never read more than [the] usable fuel." In the period between the calibration and the accident, there were no maintenance write-ups or actions concerning the fuel quantity indication system. Fueling Procedures Spur Aviation Services' Operations Manual (OM) contained the following statements regarding the pilot-in-command's (PIC) responsibilities with regard to fuel: - The PIC "is responsible for fueling...his aircraft...at all times." - "…fueling of aircraft at any location shall be performed by the Pilot in Command or by any other company personnel under his supervision…" - "It shall be the responsibility of the Pilot in Command to check the amount of fuel serviced at each station and correlate this amount with the total fuel as reported by the servicing agent and as indicated by the fuel gauges." In addition, the Spur Aviation Services fuel system ground training presentation module contained the following two statements: - "Pilots must be present during refueling" - "At each refueling [the] pilot will remove and reinstall fuel cap themselves" The pilot reported that he was present during the fueling of the airplane. However, the fixed base operator line personnel stated that the pilot left the airplane before refueling was completed. The investigation did not determine whether the pilot removed and reinstalled the fuel cap, or whether he cross-checked the serviced and indicated fuel quantities. The ATGS reported that he had assisted in the refueling of the airplane, which was contrary to the BLM contract for the airplane. The contract stated that BLM "personnel are not involved with refueling of contract aircraft unless the pilot has determined that it is an absolute necessity due to an emergency situation." However, the BLM guidance (IASG) was in conflict with that contract, since it required the ATGS to "confirm the fuel supply and flight time available for the flight." Flight Planning and Fuel Burn Spur Aviation Services' OM stated that the PIC "Prepares or supervises preparation of a flight plan considering such factors as altitude, terrain, weather, range, weight, [and] fuel." The pilot's company-provided fuel system ground training was provided to, and acknowledged by, the pilot on May 23, 2012. The associated presentation cited an "Overall fuel burn" of 30 gallons per hour (gph). According to Spur Aviation Services personnel, that value was to be used for general fuel planning purposes. The airplane manufacturer's performance and flight planning data indicated that cruise fuel burn rates ranged between 17 and 31 gph as a function of power and mixture settings. The climb fuel burn rates were considerably higher. The actual flight profile, including altitudes and power settings, was not able to be determined. As noted previously, for the majority of the flight, the weather in the area was characterized by strong and gusty winds, with rain and thunderstorms. Strong winds and associated turbulence can affect fuel usage, particularly if the pilot varies engine power to maintain a relatively constant location relative to the fire. The pilot reported that his technique for operating in those conditions was to set the engine power for a fuel burn rate of approximately 30 gph, and let the airspeed vary. The airplane was equipped with a cockpit fuel flow gauge, but no information regarding its accuracy was obtained by the investigation. The pilot departed the fire area for a return to EKO about 1730, which was 4 hours and 15 minutes after takeoff, and approximately 14 minutes prior to fuel exhaustion. The pilot reported that even though the fuel gauge registered a quantity of 0 gallons, his time- and fuel-flow-rate based calculations indicated that he should still have had "25 to 35 gallons" remaining. Review of the airplane's previous 13 flights in the week leading up to the accident flight revealed that the accident flight was the longest, by 0.2 hours, and that the next longest flight was 3.0 hours. Calculated fuel burn rates for those flights ranged between 24.6 and 36.6 gph. The actual fuel burn rates could not be determined, because the calculations presumed that the tanks were completely filled prior to each flight, and that presumption could not be verified. Records indicated that the most recent fueling prior to the accident flight was accomplished at a tachometer time of 1,279.5 hours, and that 80.4 gallons of fuel were uploaded. The tachometer registered 1,284.0 hours at the time of the accident. If the tanks were completely filled (156 gallons) prior to the flight, the calculated average fuel burn would be 34.7 gph. If the tanks contained the maximum indicated quantity (135 gallons), the calculated average fuel burn would be 30.0 gph. Spur Aviation Services did not have a company-specific policy for reserve fuel requirements; instead, the company deferred to 14CFR Part 135 fuel reserve requirements, which required a 30-minute fuel reserve for visual flight rule (VFR) operations. Using the nominal fuel burn rate of 30 gph, a 30-minute fuel reserve would be 15 gallons, which in turn would be depicted on the fuel quantity indicator with the needle located between the second (10 gallons) and third (20 gallons) index marks. Pilot-ATGS Briefing and Coordination Procedures Portions of the BLM guidance, exclusive-use contract, and training information indicated that the ATGS had certain flight-related responsibilities in addition to his mission responsibilities, and that he could be used as a resource to assist the pilot. Although the IASG specified those briefing requirements, the BLM contract did not incorporate the IASG requirements by reference, and it did not explicitly require the pilot to provide a pre-flight mission briefing to the ATGS regarding fuel requirements or limits. Therefore, the guidance for the pilot (the contract) was incongruent with the guidance for the ATSG (the IASG). According to a representative of the DOI Office of Aviation Services, previous attempts to include preflight mission briefing requirement in the DOI guidance, in order to harmonize contractual and IASG requirements, have been unsuccessful. Neither DOI nor BLM documents (including the IASG) addressed or required the establishment of a pre-determined minimum fuel value which, when reached, would require the aircraft to depart the operating area and return to its base. In addition, neither agency's documentation required periodic communication of aircraft fuel state, either intra-cockpit (aircrew), or between the aircraft and the ground (via dispatch or flight following). The ATGS and pilot had flown together on multiple fire missions. The ATGS reported that he and the pilot did not conduct the mission brief required by his guidance, which would have included several fuel-related aspects, for the flight. He also reported that they did not discuss roles and responsibilities during an emergency, which was also required by his IASG guidance, but he did not explain the reason for the lapse. Situational Awareness The Pilot's Handbook of Aeronautical Knowledge (PHAK, FAA-H-8083-25) defined situational awareness as the "accurate perception of the operational and environmental factors that affect the airplane, pilot, and passengers during a specific period of time." The PHAK stated that a situationally aware pilot "has an overview of the total operation and is not fixated on one perceived significant factor." The PHAK stated that "some of the elements inside the airplane to be considered are the status of airplane systems," and cautioned that "an awareness of the environmental conditions of the flight... and its relationship to terrain, traffic, weather, and airspace must be maintained." Risk Management The following paragraphs describe the underlying concepts of hazard, risk, and risk management, and have been paraphrased from the FAA Risk Management Handbook (FAA-H-8083-2). A hazard is a condition, event, object, or circumstance that could lead to or contribute to an unplanned or undesired event such as an accident. Risk is the future impact of a hazard that is not controlled or eliminated. Risk is the product of two elements; the likelihood of the occurrence of the hazard, and the severity of the hazard. Risk management is the method used to contr
A loss of power due to fuel exhaustion. Contributing to the accident were the pilot's failure to comply with required fueling procedures and the pilot's poor decision-making in not monitoring his fuel gauge and turning back when it reached minimum fuel.
Source: NTSB Aviation Accident Database
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