# NTSB ANC97FA159: de Havilland DHC-2, N4787C, Ketchikan, AK, September 30, 1997 - Type: NTSB accident investigation - Classification: Accident · Fatal · Field investigation · Final report - Date: September 29, 1997, 17:47 local (Sep 30, 1997, 01:47 UTC) - Place: Ketchikan, AK - Coordinates: 55.610401, -131.579971 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=55.6104&lon=-131.5800&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed, report April 15, 1999 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 2943 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC97FA159 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/2943/pdf - Page: https://openairdocs.org/ntsb/ANC97FA159 ## Probable cause The pilot's excessive climb and turning maneuver at low altitude, the pilot's inadvertent stall, and the intentional operation of the airplane with the required stall warning system disabled. Factors associated with this accident were the pilot's overconfidence in the modified airplane's ability, the uninstalled ventral fin, inadequate compliance with the STC by the company, unclear information by the manufacturer, and inadequate surveillance by the FAA. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Abrupt maneuver, takeoff - initial climb - climb - excessive, pilot in command (cause) - low altitude flight/maneuver - performed, pilot in command - overconfidence in aircraft's ability, pilot in command (contributing factor) - Loss of control - in flight, maneuvering - turn to reverse direction - stall warning system - disabled (cause) - information unclear, manufacturer (contributing factor) - vertical stabilizer surface - not installed (contributing factor) - acft/equip,inadequate compliance determination, company/operator management (contributing factor) - inadequate surveillance of operation, faa(organization) (contributing factor) - stall/spin - inadvertent, pilot in command (cause) - In flight collision with terrain/water, descent - uncontrolled ## Analysis The float equipped airplane was observed taking off in light winds and calm water, and obtaining a steep climb and nose high attitude. Witnesses described hearing no reduction of engine noise from takeoff power to climb power. The airplane entered a steep left bank about 200 feet above the water, then rolled rapidly to the right and impacted at a steep angle into the water. The airplane had been modified with a Short Take Off and Landing (STOL) kit. Certification flight tests had determined that this modification eliminated aerodynamic warning of impending stalls, and therefore required an audible stall warning. Test results also required the addition of both a ventral fin, and horizontal stabilizer finlets, to meet directional stability certification. These tests determined that the least stable condition was in the takeoff flap configuration, during climb. The Supplemental Type Certificate (STC) for the modification required the ventral fin, and an audible stall warning system be installed. The manufacturer provided a marketing video, produced prior to the STC approval, which stated the stall warning system was not required in the U.S. The company indicated this tape was used for training, and was a basis for pilots routinely disabling the stall warning horn by pulling the circuit breaker. At the time of the accident, the airplane did not have the ventral fin installed, a takeoff flaps setting was selected, and the audible stall warning circuit breaker was in the pulled (disabled) position. The local FAA Flight Standards Office had inspected the accident airplane 14 times in the previous 29 months, and made no mention of the ventral fin not being installed. ## Factual narrative HISTORY OF FLIGHT On September 29, 1997, at 1747 Alaska daylight time, a float equipped DeHavilland DHC-2 airplane, N4787C, was destroyed when it impacted the water after takeoff from Ketchikan, Alaska. The solo commercial pilot sustained fatal injuries. The airplane was operated by Promech, Inc., of Ketchikan, as a positioning flight after the last leg of Flight 89. The flight was conducted under 14 CFR Part 91, and had departed the Ketchikan International Airport seaplane dock, to reposition to the downtown seaplane base. The downtown seaplane base is located two miles to the east, on the opposite side of Tongass Narrows from the airport dock. Visual meteorological conditions prevailed at the time of the accident, and a company VFR flight plan was on file. Witnesses described seeing the airplane takeoff westbound, enter a steep climb, and make a sharp left turn at 200 feet above the water, to the east toward downtown. Witnesses then described the airplane roll rapidly the opposite direction, and impact the water at a steep angle. None of the witnesses described hearing a reduction in engine power after takeoff. INJURIES TO PERSONS The pilot sustained head injuries, and was submerged for approximately one hour prior to recovery. DAMAGE TO AIRCRAFT The airplane was destroyed by impact forces when it impacted the water in about a 90 degrees nose down attitude. Both floats separated and were recovered. The right wing separated at the wing root and was not recovered. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with single engine land, sea, and instrument ratings. He held a valid second class medical certificate with no restrictions. At the time of the accident he had accumulated approximately 2,071 hours of flight experience, with 1,200 in float equipped DHC-2 airplanes. In the last 90 and 30 days, he had flown 306, and 83 hours respectively, all in the DHC-2. He had flown 7.3 hours on the day of the accident. The pilot was hired by the operator as a seasonal dock worker in 1992. He obtained his commercial pilot certificate on May 15, 1994. He was hired as a seasonal pilot in 1996. This was his second season as a pilot for the company. He was approved to fly all the DHC-2 airplanes operated by the company. The pilot's training record indicated that on April 12, 1997, during annual recurrent training, he received 'differences' training on the "DHC-2 4787C Baron STOL," and for "995WA Wipaire." This record showed 0.3 hours of ground training, and no flight training. According to the company, 'differences' for the STOL equipped airplane consisted of a review of a manufacturer's videotape. Initial training, received one year earlier, included flight training, to include stalls. One witness to the accident described the airplane depart in "a near vertical climb, then bank to the left." A second witness described the airplane takeoff at a "steep angle of attack." A third witness interviewed by the NTSB stated that approximately 1 to 1 1/2 weeks prior to the accident, he witnessed the same airplane and pilot depart the dock at Ketchikan airport, do an aggressive high rate of climb, and then a hard, left hand turn, to return to the direction of downtown. AIRCRAFT INFORMATION The airplane was a DHC-2 Mark-I "Beaver" manufactured by DeHavilland in June 1959. It was equipped with EDO 4930 nonamphibious floats. The airplane had always been operated on floats while owned by the company. The airplane had been modified with a Baron / STOL (Short Take Off and Landing) kit on May 10, 1993. This modification was approved under U.S. Supplemental Type Certificate (STC) number SA-1070NE, and Canadian Supplemental Type Approval (STA) number SA92-45. This STOL modification consisted of a full span contoured leading wing edge, drooped wing tips, upper wing surface stall fences, and trailing edge flap gap seals. Additionally, an electrically powered, aural stall warning horn was installed as a mandatory component in the modification kit. The company stated that the stall warning horn was not required to be operable, and that it was routinely disabled to prevent the horn from continually activating at slow speeds. The system was disabled by pulling the electrical circuit breaker located in the cockpit. The company indicated that they obtained the information that the system was not required from a training and marketing video tape provided by the manufacturer. Company personnel told the NTSB IIC that during 100 hour maintenance inspections, the stall warning system was tested to ensure it was operable. The airplane was configured with vertical "Kenmore" seaplane finlets on the horizontal stabilizer ends. The airplane was not equipped with a lower surface ventral fin. METEOROLOGICAL INFORMATION The weather at the time of the accident was clear, with winds from 300 degrees magnetic at 5 knots, favoring departures to the west from the water. The water surface was calm. AERODROME INFORMATION The seaplane dock and waterway at Ketchikan International Airport is at the western end of the airport facility. The waterway is part of Tongass Narrows, and parallels the airport's paved runway 11-29. The seaplane traffic was departing and landing to the west at the time of the accident. WRECKAGE AND IMPACT INFORMATION The airplane impacted the water about one mile west of the International Airport seaplane dock. Several boats operating in the harbor responded to the accident, and towed the airplane to a beach. The airplane was initially examined by FAA inspectors, then disassembled. The stall warning circuit breaker in the cockpit was observed in the pulled, or open, position. The airplane was loaded on a truck, and relocated to the airport for further examination. The wreckage was examined by the NTSB investigator-in-charge on October 22 and 23, 1997, after relocation to the Ketchikan airport. The right wing was not recovered. Inspection of the right wing attachment fitting revealed shiny, jagged, fractures, all deformed in an aft direction. The entire left wing leading edge exhibited aft crushing which ended at the forward spar. The hydraulic flap actuator was found extended to the "takeoff" position. Both floats forward compartments were ruptured. The damage to both floats extended aft to the forward spreader bars. The float attachment fittings were fractured in a fuselage forward / floats aftward direction. No indications of preimpact damage to the airframe were noted. The three propeller blades exhibited torsional twisting toward the blade faces. All three blades had disconnected from their respective pitch guides at the propeller dome arms. The presence of fuel was found in the carburetor and lines. No preimpact engine anomalies were noted. The stall warning electrical circuit breaker located in front of and to the right of the pilot was observed in the pulled, or "open circuit," position MEDICAL AND PATHOLOGICAL INFORMATION A postmortem examination was not performed. Hospital records indicate that the pilot sustained severe head and facial injuries. Toxicological tests provided positive results which were consistent with hospital treatment. No evidence of pretreatment substances was noted. SURVIVAL ASPECTS The pilot was submerged in 50 degree Fahrenheit water for approximately one hour prior to being recovered by divers. He was resuscitated and transported to Ketchikan General Hospital for treatment. He was further transported to Seattle, Washington. The pilot did not regain consciousness, and died one day later. TESTS AND RESEARCH Examination at the NTSB metallurgical laboratory of the float attachment flying wires revealed no preimpact damage. Certification approval of the "Baron STOL" kit was conducted initially in Canada. Follow on certification was received from the FAA on the basis of a bilatera ## Aircraft - Registration: [N4787C](https://openairdocs.org/aircraft/N4787C), registered now, S/N 1330 (OpenAirDocs) - Reported make and model: de Havilland DHC-2 - Registry model: [Dehavilland BEAVER DHC-2](https://openairdocs.org/model/dehavilland-beaver-dhc-2) (registry code 2800108) (OpenAirDocs) - Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs) - Category: Airplane - Serial number: 1330 - Airframe hours: 24267 - Engines: P&W R-985 450 horsepower reciprocating - Damage: Destroyed - Flight: Positioning, Part 91 - Operator: Promech Air, Inc. - Registered owner: Kevin Hack - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, September 17, 1997, 32 hours before - Departed: KTN, KETCHIKAN IAP, AK - Destination: 5KE, KETCHIKAN HARBR, AK - Flight plan: Company VFR - Airport: KTN, Ketchikan International, runway 29, water ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 27; commercial; airplane ratings: single-engine sea, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 2,071 total, 1,200 in this make and model, 1,921 as pilot in command, 306 in the last 90 days, 83 in the last 30 days, 7 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 300° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 50 °F, dew point 43 °F - Altimeter: 29.00 inHg - Observed at: KTN, 1 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19970930029199A](https://openairdocs.org/incident/19970930029199A), Sep 30, 1997: Dhav DHC2*, Ketchikan, AK, Destroyed, 1 fatal. Witness observed steep turn on climbout. Rolled over top and dove into water indicates accelerated stall. ## Other investigations on N4787C (2) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB ANC13LA068](https://openairdocs.org/ntsb/ANC13LA068), Jul 24, 2013: Dehavilland Beaver DHC 2 (N4787C), Thorne Bay, AK, substantial damage. Probable cause: The failure of the No. 1 linkrod bushing or the bottom portion of the linkrod, which resulted in a total loss of engine power. - [NTSB SEA84FA185](https://openairdocs.org/ntsb/SEA84FA185), Jul 26, 1984: de Havilland Beaver DHC-2 (N4787C), Ketchikan, AK, destroyed, 2 fatal From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.