DCA13MA121

The operator's failure to determine the actual cargo weight, leading to the loading and operation of the airplane outside of the weight and center of gravity limits contained in the airplane flight manual, which resulted in an aerodynamic stall. Contributing to the accident was the Federal Aviation Administration's failure to require weight and balance documentation for each flight in 14 Code of Federal Regulations Part 135 single-engine operations.

Before picking up the nine passengers, the pilot loaded the accident airplane at the operator's base in Nikiski with cargo (food and supplies for the lodge). The operator of the lodge where the passengers were headed estimated the cargo weighed about 300 pounds (lbs) and that the passengers' baggage weighed about 80 lbs. Estimates of the passengers' weights were provided to the lodge operator in preparation for the trip, which totaled 1,350 lbs. The load manifest listed each of these weight estimates for a total weight of 1,730 lbs and did not contain any balance data. The cargo was not weighed, and the pilot did not document any weight and balance calculations nor was he required to do so. The airplane operator did not keep fueling records for each flight. A witness who was present during the fueling operations at the operator's base reported that he saw the pilot top off the front tank then begin fueling the center tank. The first leg of the trip from the operator's base to pick up the passengers was completed uneventfully. According to witnesses at Soldotna Airport, after loading the passengers and their baggage, the pilot taxied for departure. There were no witnesses to the accident. The airplane impacted the ground about 2,320 feet from the threshold of the departure runway and about 154 feet right of the runway centerline. An extensive postcrash fire consumed most of the airplane's cockpit and cabin area, including an unknown quantity of the baggage and cargo. Impact signatures were consistent with a nose- and right-wing-low attitude at impact. The entire airplane was accounted for at the wreckage site. Disassembly and examination of the engine and propeller revealed that both were operating during impact. Examination of the structure and flight control systems found no preimpact malfunctions or failures that would have precluded normal operation. The pilot was properly certificated and qualified in accordance with applicable federal regulations. Toxicological testing of specimens from the pilot was negative for any carbon monoxide, alcohol, or drugs. The airplane was not equipped, and was not required to be equipped, with any type of crash-resistant recorder. A video recovered from a passenger's smartphone showed the accident sequence looking out of the row 4 left seat window; the left wing and flaps are in view for most of the sequence and the flap position does not change. The investigation found that the flaps were set to the full-down (or landing) position during takeoff, contrary to recommended procedures in the airplane flight manual (AFM). The recovered video was used to estimate the airplane speed, altitude, and orientation for the portion of the flight where ground references were visible, about 22.5 seconds after the start of the takeoff roll. For the first 12 seconds, the airplane accelerated linearly from the beginning of the takeoff roll through liftoff. The pitch angle decreased slightly in the first 8 seconds as the tail lifted, remained essentially constant for about 4 seconds, and began to slightly increase as the airplane lifted off. Beginning about 14 seconds after the start of the takeoff roll, the speed began decreasing and the pitch angle began increasing. The pitch angle increased at a constant rate (about 2.8 degrees/second), reaching a maximum value of about 30 degrees, and the ground speed decreased from its maximum of about 68 mph to about 44 mph at the end of the analyzed time. The ground references disappeared from the video frame as the airplane experienced a sharp right roll before impacting the ground several seconds later. The low speed, rapid right roll, and pitch down of the airplane is consistent with an aerodynamic stall. The constant pitch rate before the stall is consistent with an aft center of gravity (CG) condition of sufficient magnitude that the elevator pitch down authority was insufficient to overcome the pitching moment generated by the aft CG. Additionally, the flaps setting at the full-down (or landing) position, contrary to procedures contained in the AFM, would have exacerbated the nose-up pitching moment due to the increased downwash on the tail and aft shift of the center of pressure; the additional aerodynamic drag from the fully extended flaps would have altered the airplane's acceleration. Using the data available, the airplane was within weight and balance limitations for the first leg of the trip. However, the cargo loaded was about 2.4 times the weight indicated on the load manifest. Further, the total weight of cargo and baggage in the cargo area, as estimated during the investigation, exceeded the installed cargo net's load limit of 750 lbs by more than 50 lbs. Although the loaded cargo actual weight was higher than indicated on the load manifest, the flight from Nikiski to Soldotna was completed without any concerns noted by the pilot, indicating that even with the higher cargo load, the airplane was within the normal CG range for that leg of the flight. Thus, based on the investigation's best estimate and a calculation of the airplane's weight and balance using the recovered passenger weights, weights and location of the luggage recovered on scene, weight of the cargo recovered on scene, and weights accounting for the liquid cargo destroyed in the postimpact fire, once the passengers were loaded, the airplane weight would have exceeded the maximum gross weight of 8,000 lbs by about 21 lbs and the CG would have been at least 5.5 inches aft of the 152.2-inch limit (a more definitive calculation could not be performed because the exact location of the cargo was not known). Additionally, the kinematics study of the accident airplane's weight and motion during initial climb and up to the point of stall found that with the pilot applying full pitch-down control input, the CG required to produce the motion observed in the video was likely just past 161 inches. Thus, the only way for the airplane motion to match the motion observed in the video was for the CG to be considerably aft of the 152.2-inch limit, which provides additional support to the results from the weight and balance study. Based on the video study, the weight and balance study constructed from available weight and balance information, and the kinematics study, the airplane exceeded the aft CG limit at takeoff, which resulted in an uncontrollable nose-up pitch leading to an aerodynamic stall. The CG was so far aft of the limit that the airplane likely would have stalled even with the flaps in the correct position. Neither 14 CFR Part 135 nor the operator's operations specifications (OpSpec) require that the aircraft weight and balance be physically documented for any flights. However, according to Section A096 of the OpSpec, when determining aircraft weight and balance, the operator should use either the actual measured weights for all passengers, baggage, and cargo or the solicited weights for passengers plus 10 lbs and actual measured weights for baggage and cargo. The operator did not comply with federal regulations that require adherence to the weighing requirements or the takeoff weight limitations in the AFM. Additionally, although the inaccurate estimate of 300 lbs for the cargo resulted in a calculated CG that was within limits for both legs of the flight, the actual weight of the cargo was significantly higher. Once loaded in Soldotna, the combination of the passengers, their baggage, and the actual cargo weight and its location resulted in the CG for the accident flight being significantly aft of the limit. With the CG so far aft, even with full nose-down input from the pilot, the nose continued to pitch up until the airplane stalled. For each flight in multiengine operations, 14 CFR 135.63(c) requires the preparation of a load manifest that includes, among other items the number of passengers, total weight of the loaded aircraft, the maximum allowable takeoff weight, and the

The airplane was not equipped, and was not required to be equipped, with a cockpit voice recorder, flight data recorder, or cockpit image recorder. No problems with communications equipment were reported. Soldotna Airport is a public, uncontrolled airport located about 1 mile southeast of Soldotna, Alaska, at a surveyed elevation of 113.4 feet. The airport features two runways: runway 7/25, which is asphalt and 5,000 feet by 130 feet, and runway 7S/25S, which is gravel and 2,312 feet by 50 feet. The runway 25 threshold is at an elevation of 112.2 feet, and the runway slopes upward at a 0.4 percent gradient. The listed obstructions to the runway are 50-foot trees located 2,265 feet from the runway and 118 feet left of the centerline that require a 41:1 slope to clear. Engine Examination Disassembly and examination of the engine revealed the following significant characteristics, consistent with rotation during impact: (1) sheared torsion shaft, (2) corresponding rotational scoring of the propeller shaft and sun gear, and (3) rotational scoring throughout the compressor and turbine sections. Metal spray was present throughout the turbine components in the air stream path. Propeller Examination Disassembly and examination of the propeller revealed the following characteristics, consistent with rotation under an amount of torque: (1) rotational scoring on the blade tips, (2) leading edge dents and tears, (3) loss of tips on two blades, and (4) similar twist and bend patterns of all four blades. There was no evidence of impression marks on the propeller hub components that could determine the blade angle prior to impact. Video Study A video of the airplane's taxi, takeoff roll, and takeoff, and brief flight was recovered from a passenger's smartphone and analyzed. The goal of the study was to estimate the trajectory and speed of the accident airplane based on information in the video, which recorded the scene south of the runway through the fourth window on the left side of the airplane. The useful segment of the video (about 22.5 seconds long) ended when, shortly after takeoff, the airborne airplane rolled to the right and began losing altitude. After that time, the video no longer showed any ground reference features, rendering an estimation of its location and orientation impossible. The video study indicated that shortly after takeoff, the airplane's airspeed decreased from about 68 mph to about 44 mph over a period of about 8.5 seconds and continued to decrease; the angle of attack increased from about 5 degrees to about 13.7 degrees over the same period of time and continued to increase. About 11 seconds after takeoff, flight speed and angle of attack reached levels consistent with an aerodynamic stall. The airplane developed a large right-wing-down roll angle and impacted the ground several seconds later. See the Video Study in the public docket for this accident for details of the study. Flap Setting The recovered video showed the left wing and flaps for the duration of the flight and revealed that the flap position did not change. In order to determine the flap setting on the accident airplane, investigators examined two similar DHC-3 airplanes and photographed the view from the fourth window on the left side of the airplane at various flap settings. The photographs and a frame from the video were scaled so that representative dimensions could be measured. The example airplanes had the flaps set to the full down or landing position when they matched the setting observed in the video. Weight and Balance Study The airplane's maximum gross weight was 8,000 lbs with an established and certificated CG range from 135.8 in to 152.2 in. Pilot and Passenger Weight and Loading The accident airplane was configured to carry a pilot and 10 passengers with one passenger able to sit in the right front seat. For the accident flight, the airplane was carrying the pilot and 9 passengers. Photographic evidence was obtained from a cell phone and a digital camera that were recovered in the wreckage. The photos were taken from the exterior as the passengers were loading the airplane and from the interior after all were loaded and the doors were closed. To estimate the airplane occupants' weight, the Alaska State Medical Examiner weighed each victim before autopsy with all clothes removed but noted that all victims sustained thermal damage and degradation. Additionally, an e-mail from the destination lodge contained the passenger weights (1,345 lbs total) reported by one of the adult male passengers in preparation for the trip. Based on the photos and the recovery location of each passenger, the seating location of each passenger was determined and matched to the estimated weights determined by the Alaska State Medical Examiner and the e-mail from the lodge. The load manifest provided by Rediske Air listed a total passenger weight of 1,350 lbs, consistent with the e-mail reported weights. Cargo/Baggage Weight and Loading During recovery at the accident site, all identifiable baggage and personal effects were separated from the identifiable cargo to be weighed. Eight unique pieces of baggage were recovered. All sustained fire damage and weighed 187 lbs in total. The load manifest obtained from the operator after the accident listed a total passenger baggage weight of 80 lbs; the e-mail provided by the destination lodge indicated that the passengers would consolidate their items into two bags, each weighing 40 lbs. Examination of the photographic evidence identified the location of several items of baggage carried on by the passengers. The passenger in the right front seat did not carry a bag on the airplane. The passenger in the row 1 left seat had a purse or satchel, and the passenger in the row 1 right seat had a backpack during the loading of the airplane. The passenger in the right seat placed her bag on the floor at her feet; the bag location for the left seat passenger was not visible in the photographs once the airplane was loaded. The row 2 passengers did not carry bags on the airplane. The row 3 passengers each had a backpack on their laps. The row 4 passenger had a backpack during the loading of the airplane but its location was not visible in the photographs once the airplane was loaded. The row 5 passenger had a backpack and a camera bag that were placed on the floor at his feet. A large roller bag was placed in the passenger area forward of the cargo net at the location of the row 5 left seat. Photographs showed this bag in an upright position before takeoff. There was no evidence in the photographs of any restraining devices on the baggage located in the passenger cabin forward of the cargo net. Three of the passenger bags carried in the cabin were not recovered in the wreckage and were likely consumed in the postcrash fire. Three additional pieces of baggage were recovered in the wreckage that were not shown in any of the photos. These items were included in the total weight of recovered baggage and assumed to be in the cargo compartment consistent with their recovered location. Almost all of the recovered cargo had some amount of fire damage and an unknown quantity was consumed by the postcrash fire. Only those items that could be conclusively identified as food or supplies were retained and weighed. These items weighed 613 lbs in total. The load manifest listed a total cargo weight of 300 lbs. The lodge operator was present during the loading of the airplane and stated that the cargo was not weighed before being loaded. He stated that he assisted with the loading by handing all of the cargo to the pilot who loaded it in the airplane. The photographic evidence shows the pilot fastening the cargo net, which was installed at the forward end of the baggage area, before the passengers boarded; no cargo was carried in the passenger area of the airplane. Food debris collected in the wreck