HALIBUT COVE, AK, USA
N756AD
Cessna U206G
The float-equipped airplane departed from water into gusting winds downwind of high, steep terrain. Witnesses said the airplane did not climb above 200 feet agl, which was insufficient to clear terrain at the upwind end of the lake. The airplane entered a steep left bank and turned within the confines of the upwind end of the lake. This turn was in a downwind direction, directly downwind of a 2,600-foot high peak. The airplane abruptly pitched nose down, impacted the water in a vertical attitude, and immediately sank. Postaccident inspection disclosed the flaps were extended to 25 degrees. The propeller separated from its mounting studs, leaving metal deposited in the majority of threads. No evidence of preimpact mechanical anomalies was discovered with the airplane. An air taxi pilot who arrived at the lake immediately after the accident reported gusts and turbulence too strong to attempt to land. He reported winds at the lake as 30 knots, stronger above, with gusts visible on the water.
HISTORY OF FLIGHT On August 11, 1997, at 1700 Alaska daylight time, a float equipped Cessna U206G, N756AD, was destroyed when it impacted water and sank shortly after takeoff from Leisure Lake (also known as China Poot Lake), four miles south of Halibut Cove, Alaska. The commercial certificated pilot, two passengers, and one dog, sustained fatal injuries. The airplane was operated by Halibut Cove Air, LLC, of Homer, Alaska. The flight was conducted under 14 CFR Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident. No flight plan was filed. The flight departed from the Beluga Lake Seaplane Base, Homer, about 1600, after refueling. The flight stopped briefly in Halibut Cove, where the pilot's wife disembarked, and the pilot's brother-in-law boarded the airplane. The flight then departed Halibut Cove and landed at Leisure Lake. The pilot's brother-in-law left and remained on shore, and two other passengers boarded the airplane. The accident was witnessed and reported by a husband and wife who live at the southeast end of Leisure Lake. The husband is a certificated commercial pilot. These witnesses were interviewed in their home by the investigative team. According to the witnesses, the airplane was flying southeast, into the wind, toward the head of the lake at an altitude of 100 feet to 200 feet above the lake. This altitude was described as insufficient to clear terrain at the head of the lake. The airplane was observed entering a steep left bank, in a downwind direction. The airplane rapidly pitched nose down, impacted in a vertical attitude, and immediately sank. They described hearing loud engine noise until impact. The couple responded in a boat, but no occupants were observed exiting the airplane. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with single engine land and sea, and instrument airplane ratings. He also possessed a Swiss private pilot certificate with an airplane, single engine rating. He was a citizen of Switzerland, and a seasonal resident of Halibut Cove. The pilot had accumulated about 800 hours of total flight experience, all in single engine airplanes. 345 hours were in seaplanes, 180 hours in the Cessna U206. In the previous 90 and 30 days, the pilot had flown an estimated 125 and 37 hours, respectively. His most recent biennial flight review was performed in the accident airplane on June 23, 1997. This was a flight check for a commercial pilot certificate. After the flight check, he began to do business as Halibut Cove Air, LLC, conducting air tour flights under 14 CFR Part 91, within 25 nautical miles of Homer and Halibut Cove. METEOROLOGICAL INFORMATION There was no record that the pilot had obtained a weather briefing. The terminal forecast for Homer at 1700 called for southeast winds at 15 knots gusting to 25 knots. No recent Pilot Reports were available for the area. The couple who witnessed the accident described daylight, visual meteorological conditions, with overcast ceilings higher than the surrounding 2,600 feet above mean sea level (msl) terrain. They described the winds as "strong from the southeast, with 'cat paw' like impressions visible on the water." These witnesses said the wind gusts began within 30 minutes prior to the accident. The closest official weather observation station is Homer, located 12 miles to the west, on a magnetic bearing of 280 degrees. At 1648, the FAA Homer Flight Service Station reported winds of 120 degrees at 5 knots. One hour later, the reported winds were 200 degrees at 12 knots, gusting to 22 knots. The Winds Aloft Forecast for the time of the accident forecast the winds between 3,000 and 9,000 feet msl to be a southeasterly flow at 40 knots. A 2,600 feet msl ridge was located 1/2 mile southeast of the 168 feet msl lake. The pilot's wife left airplane at Halibut Cove at 1615. She stated to the NTSB investigator that the winds were calm when the airplane departed for Leisure Lake, and that by 1730, the winds had picked up and were gusting. The pilot's brother-in-law, who flew from Halibut Cove to Leisure Lake at 1630, told the NTSB investigator that "the trip into the lake was not too bumpy." A photograph developed from film in one of the fatally injured passenger's camera, depicted the accident airplane beaching at the Leisure Lake site where they got on board. A second photograph shows the airplane with its nose turned out from this beach. This beach was at the downwind (northeast) end of the lake, and the views are looking south. The water in both these photographs appears calm, with wind ripples visible in the background. An air taxi pilot, who flew to the lake from Homer to assist, stated to the NTSB investigator that by 1700 the airplane had sunk. He described winds blowing 20 to 30 knots at the surface of the lake, with stronger winds above. He described turbulence and downdrafts visible on the surface of the water. He said that the winds were too turbulent to descend to the lake to attempt to land. WRECKAGE AND IMPACT INFORMATION Leisure Lake is located at 59 degrees 32.3 minutes north latitude, 151 degrees 11.9 minutes west longitude. The surface of Leisure Lake is 168 feet msl. The terrain that surrounds the lake is steep and mountainous, with a 2,600 feet msl ridge and peak 1/2 mile east-southeast. The lake is approximately 1 mile long and 2,000 feet wide. The southeast end of the lake has a ridge that is approximately 250 feet higher than the lake. This was the upwind end of the lake at the time of the accident. The passengers were picked up at a cabin located at the northwest end of the lake. The accident site was not visible from this cabin. The airplane impacted the water surface, and sank in 80 feet of fresh water. Recovery was completed by salvage divers on August 16. The divers attached flotation devices to the airplane, and then winched it onto a steep beach. All wreckage was recovered except for the propeller. The National Transportation Safety Board investigator-in-charge (IIC) examined the wreckage at the accident site on August 16, 1997. The four engine mounts were broken free of the airframe. The engine remained attached to the airplane by control cables. The propeller was missing from the engine and remains missing. The propeller mount studs were intact, and the majority of threads were full of metal deposits. The left wing fuel tank contained a clear, blue fluid that smelled like gasoline. The right wing tank was ruptured. The fuel selector valve was observed in the "left" position, and could be operated freely. All flight control cables were intact. The wing flaps were extended 25 degrees. The flap control handle was in the full down (30 degree) position. Rudder and elevator trim settings were neutral. Both wings' leading edges exhibited chord-wise crushing along the entire leading edge. The horizontal and vertical stabilizer leading edges were relatively undamaged. The floats remained attached by cables. The bow compartments of both floats were ruptured, and were deformed upwards approximately 90 degrees from the forward spreader bars. Both float upper attachment fitting bolt holes were torn out in a fuselage forward (float aft) direction. The left float exhibited slightly more damage than the right float. The electric stall warning horn operated normally when voltage was applied across its terminals. No evidence of preimpact anomalies were discovered with either the airframe or engine. MEDICAL AND PATHOLOGICAL INFORMATION The pilot held a valid second class medical certificate issued on February 17, 1997, with the restrictions that it was valid for one year, and that he possess glasses for near vision. A postmortem examination of the pilot was conducted under the authority of the Alaska State Medical Examiner, 5700 E. Tudor Road, Anchorage, Alaska, on August 14, 1997. No preexisting conditions were noted. The cause of death of the pilot was attributed to drowning. The medical examiner's report stated that injuries to the pilot would have been expected to result in unconsciousness. Toxicological tests on both front seat occupants were unremarkable. SURVIVAL ASPECTS When recovered by divers, the front seat occupants were still restrained by lap and shoulder harnesses, and the rear seat occupant by a lap belt. All four seats had separated from their respective seat tracks in a forward direction. The divers reported the doors had not been opened. ADDITIONAL INFORMATION The Safety Board released the wreckage to Alaska Claims Service of Wasilla, Alaska, on August 16, 1997. No parts or components were retained.
The pilot's improper evaluation of the weather conditions which led the pilot to maneuver within the confines of the lake to avoid surrounding terrain and a subsequent inadvertent stall. Factors were the terrain-induced turbulence and gusts.
Source: NTSB Aviation Accident Database
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