Chignik Lake, AK, USA
N803TH
CESSNA 208B
The airline transport pilot was conducting a commercial visual flight rules (VFR) flight. A passenger who was on the first segment stated that the pilot flew the airplane lower than usual for that route, and that the airplane flew through clouds during the flight. The passenger disembarked and the pilot departed on the second segment of the flight with a load of mail. The route included flight across a peninsula of mountainous terrain to a remote coastal airport that lacked official weather reporting or instrument approach procedures. About 28 minutes after departure, an emergency locator transmitter (ELT) signal from the airplane was received and a search and rescue operation was initiated. The wreckage was located about 24 miles from the destination in deep snow on the side of a steep, featureless mountain at an elevation about 3,000 ft mean sea level. The accident site displayed signatures consistent with impact during a left turn. Examination of the airplane revealed no evidence of mechanical malfunctions or anomalies that would have precluded normal operation. The airplane was not equipped with any recording or flight tracking devices, nor was it required to be; therefore, the airplane's flight track before the accident could not be determined. The airplane was certified for instrument flight and flight in icing conditions and was equipped with a terrain avoidance warning system (TAWS) which was not inhibited during the accident. Although the TAWS should have provided the pilot with alerts as the airplane neared the terrain, it could not be determined if this occurred or if the pilot heeded the alerts. A review of nearby weather camera images revealed complete mountain obscuration conditions with likely rain shower activity in the vicinity of the accident site. Visible and infrared satellite imagery indicated overcast cloud cover over the accident site at the time of the accident. The graphical forecast products that were available to the pilot before the flight indicated marginal VFR conditions for the entire route. There was no evidence that the pilot obtained an official weather briefing, and what weather information he may have accessed before the flight could not be determined. Additionally, the cloud conditions and snow-covered terrain present in the area likely resulted in flat light conditions, which would have hindered the pilot's ability to perceive terrain features and closure rates. Based on the weather camera, surface, and upper air observations, it is likely that the pilot encountered instrument meteorological conditions inflight, after which he performed a left turn to return to visual meteorological conditions and did not recognize his proximity to the mountain due to the flat light conditions. The pilot and the dispatch agent signed a company flight risk assessment form before the flight, which showed that the weather conditions for the flight were within the company's acceptable risk parameters. Although the village agents at the departure and destination airports stated that the weather at those coastal locations was good, the weather assessment for the accident flight was based on hours-old observations provided by a village agent who was not trained in weather observation and did not include en route weather information, the area forecast, or the AIRMET for mountain obscuration effective during the dispatch time and at the time of the accident. Since acquiring the accident route from another operator years earlier, the company had not performed a risk assessment of the route and its associated hazards. Multiple company pilots described the accident route of flight as hazardous and considered it an undesirable route due to the terrain, rapidly changing weather, and lack of weather reporting infrastructure; however, the company did not address or attempt to mitigate these known hazards through its risk assessment processes. The company's controlled-flight-into-terrain (CFIT)-avoidance program stated that each pilot shall have one classroom training session and one CFIT-avoidance training session in an aviation training device (ATD) each year; however, the pilot's training records indicated that his most recent ATD session was 15 months prior. More recent CFIT avoidance training may have resulted in the pilot recognizing and responding to the reduced visibility and flat light conditions sooner.
HISTORY OF FLIGHTOn May 1, 2017, about 1350 Alaska daylight time, a Cessna 208B airplane, N803TH, sustained substantial damage after impacting steep, mountainous terrain near Chignik Lake, Alaska. The airline transport pilot was fatally injured. The airplane was operated by Grant Aviation, Inc., as a Title 14 Code of Federal Regulations (CFR) Part 135 non-scheduled mail contract flight. Instrument meteorological conditions (IMC) existed at the accident site and company flight following procedures were in effect for the visual flight rules flight, which departed Port Heiden Airport (PAPH), Port Heiden, Alaska, at 1325, destined for Perryville Airport (PAPE), Perryville, Alaska. The pilot's flight and duty records indicated that he reported for duty about 0800 the morning of the accident. The pilot was scheduled for a six-segment route the day of the accident, originating from King Salmon Airport (PAKN), King Salmon, Alaska; the accident occurred on the second segment. The flight departed on the first segment at 1215 and proceeded to PAPH, arriving at 1313 with one passenger, who disembarked at PAPH. The passenger, who was a private pilot who often flew on Grant Aviation flights, reported that the pilot flew the segment lower than usual due to low clouds and that the pilot flew through clouds during the flight. The village agent who assisted the pilot on the ground stated that he appeared to be in good spirits. The airplane departed PAPH at 1325. The destination airport was about 80 miles south and located in a remote coastal area that did not have official weather reporting or instrument approaches available. The route required crossing the Aleutian Peninsula and mountainous terrain with elevations between 2,900 ft and 4,600 ft. The airplane's route of flight during this segment could not be determined as the area was not covered by radar service and the airplane was not equipped with tracking equipment. At 1353, the Grant Aviation director of operations (DO) was notified that the US Coast Guard had received a 406-MHz emergency locator transmitter (ELT) signal from the accident airplane. The DO initiated the company's overdue aircraft procedures. The wreckage was located at 1730 about 24 miles northeast of PAPE on a steep, snow-covered mountain. A rescue crewman was hoisted down to the site and determined that the pilot, who was inside the cockpit and strapped in his seat, had received fatal injuries. See figures 1 and 2. Figure 1. VFR Sectional chart with the accident site indicated. Figure 2. Accident site. PERSONNEL INFORMATIONThe pilot, age 54, held an airline transport pilot certificate with an airplane multi-engine land rating and commercial privileges for airplane single-engine land and sea and glider. He held a flight instructor certificate for airplane single-engine and multi-engine, instrument airplane, and glider. Company training records indicated that he had accumulated 4,989 hours of flight experience with over 904 hours in Cessna 208B airplanes. His most recent Federal Aviation Administration (FAA) second-class airman medical certificate was issued on March 13, 2017, with the limitation that he must wear corrective lenses. The pilot's personal logbooks were not located. A review of company personnel records indicated that the pilot completed initial company training and was assigned as pilot-in-command (PIC) on the Cessna 207 on October 16, 2014. He was assigned PIC in the Gipps Aero GA-8 airplane on May 19, 2015. He completed initial Cessna 208B training and check rides on March 3, 2016 and was subsequently assigned as PIC in the Cessna 208B. The pilot completed his most recent required proficiency check in the Cessna 208B on April 9, 2017. The flight included an instrument proficiency check and a line check. He completed recurrent ground training, which included controlled flight into terrain (CFIT) avoidance computer based training, on November 19, 2016. His most recent CFIT avoidance simulator training was completed on January 31, 2016. A review of company flight and duty records revealed that the pilot had accumulated 87.6 flight hours in the previous month, of which 73.5 were accumulated during the previous 2 weeks while based at King Salmon. He had no flights scheduled the day before the accident. He flew the accident flight route on 9 of the previous 10 days. AIRCRAFT INFORMATIONThe accident airplane was manufactured in 1992. At the time of the accident, the airplane had accumulated 17,990.7 total flight hours and was maintained under an approved inspection program. The most recent inspection of the airframe and engine was completed on April 21, 2017. The airplane was equipped with a Pratt & Whitney PT6A-114A turbine engine rated at 675 shaft horsepower. The engine had a total time in service of 13,120.1 hours; 2,882.3 hours had elapsed since the last overhaul. The propeller was a McCauley model 3GF34C703-B. The airplane was equipped for instrument flight and flight into icing conditions and was certified for single-pilot operation. The airplane was equipped with a Garmin GNS 530 navigation system with integrated class B terrain awareness and warning system (TAWS) with visual and aural terrain alerts. A TAWS inhibit switch and TAWS inhibit light were included in the system. The Garmin GNS 530 does not retain memory. The airplane was not equipped with automatic dependent surveillance-broadcast (ADS-B) equipment, flight tracking equipment, a flight data recorder, or a cockpit voice recorder. There was no regulatory requirement for this equipment to be installed. A review of the aircraft logbook revealed that the company had been monitoring a reoccurring chip detector light. The chip detector light illuminated in flight on three occasions in February. Each time, small slivers of fuzz material were found on the accessories gearbox (AGB) magnetic chip detector. An oil sample analysis was conducted by an external laboratory, and a report dated March 31, 2017, stated that trace metallic elements were consistent with alloy steel flakes similar to AMS6260 or AMS6265, which is an alloy used for gears in the engine. The pilot's flight log for the accident flight indicated a load of 1,322 lbs of mail, a takeoff weight of 8,100 lbs, and a center of gravity of 200.5 inches. METEOROLOGICAL INFORMATIONAt the time of the accident, an AIRMET valid for the accident site forecast mountain obscuration conditions due to clouds and precipitation. The area forecast issued at 1214 predicted scattered clouds at 2,000 ft above ground level (agl) and broken ceilings at 2,000 ft and 5,000 ft with tops to 10,000 ft. The ceiling was forecast to be occasionally at 2,000 ft with isolated light rain showers and a freezing level at 1,500 ft. No turbulence or icing conditions were forecast. The Alaska Aviation Weather Unit flying weather graphic valid during the accident flight indicated marginal visual flight rules (VFR) conditions for the route of flight. The nearest official weather reporting station was Chignik Airport (PAJC), located about 18 miles northeast of the accident site. At 1239, an aviation special weather report reported variable wind at 4 knots; 10 statute miles visibility; light rain; overcast clouds at 1,700 ft; temperature 39°F, dewpoint 36°F; and an altimeter setting of 29.51 inches of mercury. The visible and infrared data from the Geostationary Operational Environmental Satellite number 15 (GOES-15) at 1300 indicated an overcast layer with mountain obscuration likely and cloud tops at 9,000 ft. FAA weather camera images from Chignik Lake, about 7 miles north-northeast of the accident site at an elevation of 45 ft, revealed ceilings between 900 ft mean sea level (msl) and 2,700 ft msl, with forward visibilities between 1.5 and 5 miles in the vicinity of the accident site around the accident time (see figure 3). The images further suggest that mountain obscuration conditions prevailed with likely rain shower activity. Figure 3. South-facing Chignik Lake FAA weather camera image on a clear day (left) and before the accident at 1347 (right). The PAPE village agent stated that the weather at PAPE was generally good on the day of the accident. She was not a trained weather observer, but she had been observing weather in the area for over 10 years and knew how to estimate ceilings and visibility distances based on surrounding landmarks. She recalled that, while she was waiting on the airplane to arrive, the clouds were 3,000 ft scattered and visibility was 10 miles. She could see north over the pass to Chignik, which meant the ceiling was at least 2,500 ft in the mountain pass. She stated that the accident pilot did not call her for a weather observation update. The dispatch agent on duty recorded airport weather information on a company form at intervals throughout the accident day. The PAPE weather entry, provided by the village agent at 1021, indicated winds from the east at 10 knots, 10 miles visibility, and an overcast ceiling of 3,500 ft. That was the sole entry for PAPE for the day, even though the flight was due to arrive at 1350. According to the dispatch agent's statement, she did not talk to the pilot or verbally provide any updates to him during the flight. The dispatch agent stated that she used the FAA Alaska weather camera website and village agent observations to document the weather for the flight. The company's General Operating Manual, page 12-5, indicated that if official weather was not available, "personal observation or other persons competent to supply appropriate observations" were permitted. A search of official weather briefing sources, such as Lockheed Martin Flight Service and Direct User Access Terminal Service, indicated that the accident pilot did not request an official weather briefing before the flight. AIRPORT INFORMATIONThe accident airplane was manufactured in 1992. At the time of the accident, the airplane had accumulated 17,990.7 total flight hours and was maintained under an approved inspection program. The most recent inspection of the airframe and engine was completed on April 21, 2017. The airplane was equipped with a Pratt & Whitney PT6A-114A turbine engine rated at 675 shaft horsepower. The engine had a total time in service of 13,120.1 hours; 2,882.3 hours had elapsed since the last overhaul. The propeller was a McCauley model 3GF34C703-B. The airplane was equipped for instrument flight and flight into icing conditions and was certified for single-pilot operation. The airplane was equipped with a Garmin GNS 530 navigation system with integrated class B terrain awareness and warning system (TAWS) with visual and aural terrain alerts. A TAWS inhibit switch and TAWS inhibit light were included in the system. The Garmin GNS 530 does not retain memory. The airplane was not equipped with automatic dependent surveillance-broadcast (ADS-B) equipment, flight tracking equipment, a flight data recorder, or a cockpit voice recorder. There was no regulatory requirement for this equipment to be installed. A review of the aircraft logbook revealed that the company had been monitoring a reoccurring chip detector light. The chip detector light illuminated in flight on three occasions in February. Each time, small slivers of fuzz material were found on the accessories gearbox (AGB) magnetic chip detector. An oil sample analysis was conducted by an external laboratory, and a report dated March 31, 2017, stated that trace metallic elements were consistent with alloy steel flakes similar to AMS6260 or AMS6265, which is an alloy used for gears in the engine. The pilot's flight log for the accident flight indicated a load of 1,322 lbs of mail, a takeoff weight of 8,100 lbs, and a center of gravity of 200.5 inches. WRECKAGE AND IMPACT INFORMATIONOn May 4, 2017, the Alaska State Troopers coordinated a recovery mission with members of the Alaska Mountain Rescue Group. The National Transportation Safety Board (NTSB) did not travel to the site due to the remote location and hazardous terrain. According to information and photographs provided by the recovery crew, the wreckage came to rest in deep snow about 2,993 ft msl on the west face of a steep, featureless mountain in the Alaska Peninsula National Wildlife Refuge. It was located about 500 ft from the top of the mountain ridge and partially submerged in the snow on its left side with the nose section under the snowpack (see figure 4). The fragmented wreckage was contained in an area about 100 ft long by 35 ft wide, on a heading of about 031° true, with the right wing separated and located about 40 ft forward of the main wreckage and a trail of debris about 30 ft behind the empennage. The initial impact area was indicated by a narrow, 30-ft-long curved indentation in the snow about 65 ft behind the wreckage, indicative of a wing tip strike. Figure 4. Aerial photograph of N803TH wreckage resting on left side of fuselage with nose under the snow pack (courtesy of the Alaska Mountain Rescue Group) A postrecovery examination revealed structural damage to the area of the fuselage between the wing spar connections, a large hole and extensive buckling on the left side of the fuselage cabin and buckling on the left rear fuselage. The forward fuselage and cockpit were separated during recovery and exhibited fractures and inward compression deformations in the structure. The right wing separated from the fuselage inboard of the wing attachment points with a section of the fuselage attached and spar deformation in a forward direction. The left wing exhibited separation at the forward attachment point with rearward overload tension signatures and compression buckling at the inboard trailing edge. The empennage was intact. The flight controls were continuous from the cockpit to the flight control surfaces with the exception of the aileron cables, which were found separated and exhibited overload signatures. The deice boots were intact with the exception of impact tears. The propeller blades were each secure in the hub and exhibited trailing edge S-bending signatures consistent with engine power at the time of impact. The propeller shaft was fractured and separated from the engine and exhibited overload signatures. The engine exhibited moderate impact damage to the exhaust duct, reduction gear box (RGB), the gas generator case, and the accessory gearbox (AGB). The power and compressor rotors rotated without noise. The compressor turbine disk and power turbine vane and disk exhibited circumferential rubbing marks. Contact marks were found between RGB first and second stage carriers, which are indicators of engine power at impact. Both magnetic chip detectors showed fuzz material on the poles. The No. 3 and 4 bearings oil scavenge pump showed severe scoring marks into the housing and on the pump gears' tips. The RGB oil scavenge pump showed similar light scoring marks and metal debris. The oil sump contained a small crushed plastic cap that was deformed in a manner that corresponded to the size and shape of the oil pump gear tips. The cap likely passed through the oil scavenge system and came to rest in the sump. Oil was present throughout the system. No preaccident anomalies were noted with the airframe or engine that would have precluded normal operation. ADDITIONAL INFORMATIONCFIT Manual Grant's CFIT Avoidance Manual defined CFIT as, "when an airworthy aircraft under the control of the flight crew is flown unintentionally into terrain, obstacles or water, usually with no prior awareness by the crew." Flat Light Flat light was defined in Grant's CFIT Avoidance Manual as "an optical illusion that causes pilots to lose their depth-of-field and contrast vision. It is usually accompanied by overcast skies inhibiting any good visual clues. …occur primarily in snow covered areas. Flat light can completely obscure features of the terrain, creating an inability to distinguish distances and closure rates." Company policy stated that VFR flight in flat light conditions was allowed provided the pilot recognized the conditions and increased minimum flight altitude to 2,000 ft above the highest obstacle within a horizontal distance of 5 miles if operating over mountai
The pilot's continued visual flight rules flight into an area of mountainous terrain and instrument meteorological conditions, which resulted in controlled flight into terrain (CFIT). Contributing to the accident was the company's failure to provide the pilot with CFIT-avoidance recurrent simulator training as required by their CFIT avoidance program and the company's inadequate flight risk assessment processes, which did not account for the known weather hazards relevant to the accident route of flight.
Source: NTSB Aviation Accident Database
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