ANC15FA071

The pilot's decision to depart in dark night, visual meteorological conditions over water, which resulted in his subsequent spatial disorientation and loss of airplane control. Contributing to the accident was the pilot's failure to determine the airplane's actual preflight weight and balance and center of gravity (CG), which led to the airplane being loaded and operated outside of the weight and CG limits and to a subsequent aerodynamic stall.

The airline transport pilot and nine passengers departed in a float-equipped airplane in dark night, visual meteorological conditions on a 14 Code of Federal Regulations Part 91 other work use flight from a fishing lodge to a remote fishing location. The pilot reported that, before the flight departed, the front and center fuel tanks were filled, and the aft fuel tank had "residual" fuel. He did not weigh the cargo nor did he document any weight and balance calculations. When asked how he calculated the airplane's weight and balance before departure, the pilot said he "guesstimated" it. According to a witness, after liftoff, the airplane began to climb and then descended, and the floats subsequently struck the water's surface. The airplane then became airborne again and veered right, but he lost sight of it behind an area of rising terrain. The pilot reported that he heard a noise from the left side of the airplane shortly after liftoff, which was likely the floats impacting the water. According to the automatic dependent surveillance-broadcast data, the airplane then began a gradual right turn before reaching a maximum altitude of 175 ft above the water. The airplane then descended toward the water's surface, flew low over the water and terrain, and then climbed briefly again before it impacted terrain. The pilot stated that he did not know that the airplane touched the water's surface after the initial liftoff or that the airplane then turned right. Impact signatures were consistent with a 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 airframe and flight control systems found no preimpact malfunctions or failures that would have precluded normal operation. A postaccident weight and balance study using the passenger weights, weighed cargo, and fuel load showed that the airplane exceeded its maximum gross weight of 8,367 lbs by about 508.6 lbs and that the center of gravity (CG) was 4.08 inches aft of the aft CG limit. Data from the airplane's automatic dependent surveillance-broadcast (ADS-B) showed that the airplane was at or below the stall speeds listed in the airplane flight manual during both the initial and second climbs. The ADS-B data show that, because the pilot failed to determine the airplane's actual preflight weight and CG and loaded and operated outside of the weight and CG limits, the airplane did not attain a proper airspeed to climb, and it experienced an aerodynamic stall. The pilot departed during dark night conditions over water and was relying on external visual cues and not the airplane's instrumentation to control the airplane. There were insufficient external cues available to the pilot to reliably control the airplane, and he was likely experiencing spatial disorientation after takeoff and the subsequent maneuvering.

Hospital treatment records revealed that the pilot had a 1-week history of right leg swelling before the accident. In addition to crash-induced injuries, the pilot was diagnosed with a right leg deep vein thrombosis and bilateral pulmonary emboli. Two days after admission, the pilot suffered a syncopal episode attributed to another pulmonary embolus. Toxicology The FAA Bioaeronautical Sciences Research Laboratory testing of the pilot's urine collected on admission to the hospital was negative for ethanol and drugs of abuse but detected ibuprofen, ketamine, and its metabolite norketamine. Ketamine is an injectable, rapidly acting general anesthetic agent that was administered during the pilot's postaccident transport to the hospital. Ibuprofen is a nonsedating medicine used to treat pain, swelling, and fever and is marketed with various names, including Motrin. (See the Medical Factual Report in the docket for this accident for more information.) Pilot and Passenger Injuries The NTSB Medical Officer reviewed hospital treatment records to determine the pilot's injuries. The IIC reviewed the Alaska State Medical examiner's autopsy reports for the three fatally injured passengers. See table 2 for a complete list of pilot and passenger injuries. Table 2 List of pilot and passenger injuries. The closest weather reporting weather station was Iliamna, about 1 mile south of the accident site. At 0553, a METAR reported, in part, wind 270° at 7 knots; visibility 10 statute miles; clouds and sky condition, scattered at 700 ft, overcast at 4,400 ft; temperature 48° F; dew point 47° F; and altimeter 29.61 inches of mercury. According to the US Naval Observatory Astronomical Applications Department, civil twilight began at 0706, and sunrise was at 0748. The pilot, age 54, held an airline transport pilot certificate with an airplane multiengine land rating and commercial pilot privileges with an airplane single-engine land rating. He also held a type rating for Beech 1900 and Beech 300 airplanes and a flight instructor certificate with an airplane single-engine land rating. According to the Federal Aviation Administration (FAA) medical certification file, the pilot was first medically certificated in 1981. His most recent FAA second-class medical certificate was issued May 12, 2015, with the limitation that he must have available glasses for near vision. At that time, he measured 71 inches tall and weighed 249 lbs. He reported no medications, and the examining physician did not identify any abnormal findings. According to the pilot's logbooks, he had about 11,280 total flight hours, about 450 hours of which were in the accident airplane make and model. In the 90 and 30 days before the accident, the pilot logged 200 and 70 flight hours, respectively. His most recent flight review was on February 9, 2014, in a Schweizer S269C helicopter. The pilot had flown for Rainbow King Lodge during the 2012 to 2015 fishing seasons. The first two seasons were before the Otter was converted to a turbine-powered airplane (see the next section for more information about the conversion). The pilot stated that he had not received any training in the airplane since the turbine conversion. The main wreckage was found about 510 ft from the shore of East Wind Lake at N59.777778 W154.917778, on a magnetic heading of 020°, about 0.5 miles from the departure point. The airplane impacted soft, tundra-covered terrain. There was no evidence of any impact with terrain between the lake and the main wreckage. There was a ground scar about 20 ft long and 10 inches deep aft and in line with the right wing. There was an additional ground scar aft of the right float that was about half the length of the right float. The left wing remained attached, and the left flap and aileron were attached at their respective attachment points. The right wing was separated from the fuselage at the wing root, and the forward attachment point bolt was broken at the wing and remained in the wing. The rear attachment, about 5 inches into the spar, was separated. The right flap was separated, and the right lift strut was separated at the fuselage structure. The last 10 ft of the right wing sustained extensive aft accordion-style crushing from the tip inboard. The right aileron had extensive impact damage and only remained attached outboard of the attachment point. The tail was displaced about 30° to the left. The stabilator remained attached and was relatively undamaged. The outboard 2 ft of the right elevator was separated, and the inboard portion of the right elevator had accordion-style crushing where it had impacted the rudder. The left elevator remained attached and undamaged. The rudder remained attached and sustained damage where it was penetrated by the servo tab. The rudder and elevator cables were still attached to their relative attachment points. The jack screw separated at the top fitting from the horizontal stabilator, and the forward bolts threads were stripped. There was no noted inner movement of the jack screw, which remained attached at the lower attachment point and measured about 3/4 inch. The left float was attached to the fuselage at the forward and aft attachment points. The forward spreader bar remained attached to the float. The left float came to rest on top of the right float. Multiple outboard panels on the left float had slight inward crushing. The right float was heavily damaged and fragmented at the attachment points. The elevator, trim indicator, and a manual control wheel were in a nose-up position. The rudder trim was in a slightly right position. The flaps were hydraulically actuated and were in the "takeoff" position. The navigation, beacon, cockpit, and instrument lights were in the "on" position, and the dome, strobe, and landing lights were in the "off" position. The propeller was still attached to the propeller flange. Three blades had extensive leading edge gouging and exhibited torsional twisting. One of the blades tip had separated, one of the blades was rotated 180° in the hub, and another blade was buried in the terrain. The power lever was slightly above flight idle. The condition lever was midrange. The fuel shut-off was not in an off position, the fuel selector was on the center tank, and the ignition was set to continuous ignition. All three of the fuel caps were on and secure. The fuselage had accordion-style crushing, and at the rear spar there was a tear in the production joint. There was no damage to the engine mounts. The accident airplane was a high-wing, float-equipped, single-pilot, de Havilland DHC-3T, N928RK, serial number 61, manufactured in 1954. It was powered by a Honeywell TPE 331-12JR-702TT turboprop engine per a Texas Turbine Conversions, Inc., supplemental type certificate (STC). It was equipped with a Hartzell model HC-B4TN-5NL four-bladed propeller. In April 2014, the airplane was sent to Recon Air Corporation in Geraldton, Ontario, Canada, for a major overhaul and the turbine conversion. The airplane's US registry was changed to N928RK. The airplane was also modified with a Baron STOL kit and an upgross kit per an STC to improve its performance. The upgross kit increased the maximum gross weight of the airplane from 8,000 lbs to 8,367 lbs. The airplane was configured to carry one pilot and 10 passengers and cargo. On May 24, 2014, after the overhaul, a new weight and balance calculation was performed, which showed that the airplane's basic empty weight on wheels was 4,345 lbs. On May 30, 2014, an 800-hour inspection of the airplane and special inspection items was completed. The records indicated that all applicable airworthiness directives were complied with at this time. According to maintenance records, the airplane's last inspection was a 100-hour inspection on July 25, 2015, at which time, the airframe had accumulated 15,436 total hours, and the engine had accumulated 384 tot