KENAI, AK, USA
N8TL
Cessna 180A
The private pilot was attempting to transit a 20 mile long mountainous pass. He had delayed his flight three times the day of the accident. Pilot weather reports (PIREPS) from pilots who had flown through the pass indicated the weather deteriorated about one mile west of the accident site to 700 feet overcast ceilings and 1 mile visibility. The PIREPS described rain, mist, and winds from the east of 25 knots, gusting to 40 knots. The airplane impacted a tree on a small ridge on the side of the valley at 950 feet msl, and came to rest 380 linear feet away, at an altitude of 700 feet msl. The final flight path was on a ground track of 060 degrees magnetic, back toward the eastern entrance to the pass. The NTSB investigator-in-charge interviewed four pilots who successfully transited the pass during the time period surrounding the accident. All four indicated that at 950 feet msl, the accident airplane would have been at or into the bases of the overcast. All four also indicated they flew through the pass between 300 and 800 feet in order to maintain visual contact with the terrain. Postaccident inspection of the airplane disclosed no evidence of any preimpact mechanical anomalies.
HISTORY OF FLIGHT On August 5, 1999, about 1348 Alaska daylight time, a float equipped Cessna 180A airplane, N8TL, was destroyed when it impacted terrain about 700 feet above sea level (msl), at 60 degrees, 48.7 minutes north latitude, 152 degrees, 28.8 minutes west longitude. This location is about two miles inside the eastern entrance to Lake Clark Pass, about 39 miles west of Kenai, Alaska. Lake Clark Pass is oriented generally east-west, with two dog-leg turns. The pass is about one mile wide at the narrowest spot, and about 20 miles long. The private pilot, and the one passenger on board were fatally injured. The flight was operated under 14 CFR Part 91 as a personal flight. The flight departed the Lake Hood Seaplane Base in Anchorage, Alaska, at 1218, for Chikuminuk Lake, Alaska. Visual meteorological conditions were reported at Anchorage and Kenai at the time of the accident, and marginal VFR conditions were reported at Big River Lakes, Alaska, about 7 miles east of the accident site. A VFR flight plan was on file. A notification that an emergency locator transmitter (ELT) signal had been received via satellite was forwarded to the Alaskan Rescue Coordination Center in Anchorage at 1438, and a search was commenced. At 1856, the wreckage was located by the crew of an Air National Guard rescue helicopter. INJURIES TO PERSONS Both occupants sustained fatal traumatic and decelerative injuries. DAMAGE TO AIRCRAFT The airplane was destroyed by a combination of impact damage, and follow on damage resulting from falling glacial ice and flood waters. PERSONNEL INFORMATION The pilot held a private pilot certificate, with airplane single engine land and sea, and instrument airplane ratings. The pilot held a second class medical certificate issued on April 23, 1998. The certificate contained the limitation "holder shall wear corrective lenses." His most recent biennial flight review equivalent (Civil Air Patrol (CAP) Form 5 flight check) was conducted on October 12, 1998. The pilot received his instrument rating on May 22, 1996. He obtained his seaplane rating on September 6, 1997. According to copies of old logbook pages, and payment records from the Civil Air Patrol, and the flying club that owned the airplane, the pilot had accumulated approximately 958 flight hours at the time of the accident. Payment records revealed 133 hours of flight experience in the previous 12 months. Records indicated the pilot had accrued about 110 hours of total instrument flight. Approximately 30 hours were in actual instrument conditions. The pilot's first flight in one of the club's two Cessna 180 airplanes was July 22, 1998. He had accrued about 70 hours of seaplane experience, and a total of 58 hours of experience in the Cessna 180A at the time of the accident. His personal logbook(s) were not located. AIRCRAFT INFORMATION The airplane was a Cessna 180A airplane, manufactured in 1958. It was equipped with EDO 89-2870 floats, and a Telelyne Continental Motors O-470K, 230 horsepower engine. The airplane was owned and operated by Opportunity Flying Club, Inc., of Anchorage, a corporation established to provide members part ownership in the two club-owned Cessna 180 seaplanes. The members operated under 14 CFR Part 91, for personal and pleasure flying. A review of maintenance records, logbooks, and weight and balance information, revealed no anomalies. The fuel contractor at Lake Hood confirmed 22 gallons of fuel were purchased by the pilot the morning of the accident, and the airplane's 62 gallon fuel tanks were full prior to departure. METEOROLOGICAL INFORMATION The official weather observations taken at Big River Lakes, Alaska, located about seven miles east of the accident site at the eastern entrance to Lake Clark Pass, on August 5 were as follows: 1155 ADT "Surface winds calm, visibility 5 miles light rain and fog, ceiling 1,000 feet overcast, temperature 57 degrees Fahrenheit (F), dew point 54 degrees F. Remarks: estimate pass closed." 1456 ADT "Surface winds calm, visibility 4 miles light rain and fog, ceiling 1,000 feet overcast, temperature 59 degrees F, dew point 54 degrees F. Remarks: estimate pass closed." The pilot of a Cessna 185 airplane who transited Lake Clark Pass in an eastbound direction, gave a pilot weather report (PIREP) to the FAA Kenai Automated Flight Service Station (AFSS) at 1217. He was also contacted by the accident pilot at 1236, just after the Anchorage Radar Approach (RAPCON) controller released the accident airplane from radar flight following. The reporting pilot told the NTSB IIC during a telephone interview on August 11, he provided the same information to the accident pilot as he did to Kenai AFSS. He indicated the weather at the west end of the pass to be 2,500 feet broken, 3,500 feet overcast, with light rain and moderate turbulence. He estimated the winds at the east end of Lake Clark Pass, at 500 feet msl, to be from the east about 25 knots, gusting to 40 knots. The reporting pilot said the ceiling at Summit Lake in the pass was overcast at 1,200 feet msl. He flew eastbound through "the narrows," located about 1 mile west of the accident site, at 500 feet above the surface, and estimated the ceiling at 700 feet msl, and the visibility as 1 mile. The reporting pilot told the IIC he warned the accident pilot to be careful going through the pass because there was a lot of traffic flying through, and the visibility was low. The pilot of a DeHavilland DHC-4 Caribou told the NTSB IIC that he flew through Lake Clark Pass westbound between 1200 and 1215. He indicated that the pass was open, and numerous airplanes were flying both directions, including a C-46. He said the visibility was 2 miles, and the ceilings were low and indefinite. He said he transited the pass about 500 feet above the ground, and that visibility deteriorated if he climbed higher. He stated that between 1,000 and 1,200 feet msl, an aircraft would have been in the clouds. The NTSB IIC interviewed the pilot of a DHC-2 who flew through Lake Clark Pass about 1200 in a westbound direction. The DHC-2 pilot said that he flew through "the narrows" at 800 feet msl. He stated at that altitude he was right at the bases of the overcast cloud layer. The PIREP he gave to Kenai AFSS stated at "the narrows" the ceiling was 800 feet msl. The NTSB IIC interviewed the pilot of a PA-18 super cub who flew through Lake Clark Pass eastbound and talked to the DHC-2 pilot, the C-185 pilot, and the accident pilot. He described a 30 knot wind from the east at 300 feet above the ground at the east entrance to the pass. He estimated the ceiling about 1,000 feet msl, and visibility about 3 miles with "mist fingers" on the mountains in the pass. He said the visibility was lowest at the east end of the pass. The PIREP he provided to Kenai AFSS stated "weather slopes down to east end of the pass with scattered clouds at 500 feet, overcast ceilings at 1,000 feet msl, and visibility 3 miles." He indicated he never saw the opposite direction C-46, or DHC-4, traffic which he passed. He believed that 950 feet msl would have been right at the bases of the clouds. COMMUNICATIONS The pilot made several telephone calls to the FAA Kenai AFSS on the day of the accident. At 0603 he requested a standard weather brief for the trip from Lake Hood Seaplane Base in Anchorage, through Lake Clark Pass, on to Chikuminuk Lake, 75 miles northwest of Dillingham, Alaska. He was told at 0607 that Lake Clark Pass was forecast to be marginal VFR due to ceilings and rain. The pilot filed his flight plan to depart at 0900. At 1003 he called Kenai AFSS and requested an updated briefing. He told the briefer he now wanted to depart at 1100, and amended his route to include a fuel stop in Port Alsworth, located at the west end of Lake Clark Pass. At 1004, the briefer told the pilot "Big River Lakes, they've come down...visibility is two miles. Winds calm, visibility two, light rain, fog, ceilings 1,000 feet overcast, temperature 13, dew point 12...estimated pass to be closed....the pilot report by the beaver was at 0945. Showed the east end was 1,000 broken, 3,000 overcast, 10 miles and light rain...." At 1008, the briefer said "let me check Big River Lakes, maybe we got the new one. Yeah, here new Big River Lakes, winds calm, visibility four, light rain, mist, ceiling 1,500 overcast." At 1126 the pilot called Kenai AFSS on the radio, and said "I'm still on the water here at Lake Hood. I have a VFR flight plan on file. Departure was supposed to be 1100, I would like to make it 1200." At 1129, the Flight Service specialist passed "Big River Lakes, visibility 10, light rain, mist, ceilings 1,500 overcast, temperature 14, dew point 12, estimate pass closed." He then passed "I've had pilot reports on turbulence getting bad....Piper Cub, winds 140 at 35, moderate to severe, moderate and greater turbulence attempting Telequana Pass to Lake Clark Pass. He says the pass might be open, but he turned around due to turbulence." At 1132 the pilot asked "so no pilot reports through Lake Clark Pass?" The AFSS briefer replied "other than that one that tried to go through from the north...that ran into the turbulence." At 1219, the Lake Hood air traffic control tower (ATCT) cleared N8TL for takeoff. At 1236, Anchorage RAPCON terminated radar services for N8TL as the airplane departed the RAPCON's service area westbound. The accident pilot overheard another airplane, N185SP, check onto the RAPCON frequency eastbound. The accident pilot asked N185SP to go to a different (untaped) frequency for a PIREP from Lake Clark Pass. At 1241, the pilot activated his VFR flight plan with the Kenai AFSS. He said he was off of Lake Hood at 1225, and stated his position was just west of Beluga (about 40 miles east of the accident site). About 1644, the Flight Service specialist on duty at the FAA Dillingham FSS, received a telephone call on an unrecorded line. The specialist told the NTSB IIC that an unidentified male closed a flight plan for N8TL to Chikuminuk Lake. The specialist said the reception was bad, and difficult to hear. No one was located by the NTSB IIC who made, or could explain, the telephone call. Interviews with the fuel contractors in Port Alsworth, at the west end of Lake Clark Pass, determined that the airplane did not land at Port Alsworth to refuel, as the pilot had indicated on the final revision of his flight plan. WRECKAGE AND IMPACT INFORMATION The NTSB IIC began his on-site investigation on August 6, accompanied by an FAA inspector, and two Alaska State Troopers. The wreckage was initially located at 700 feet msl, about 1,000 feet directly beneath a hanging glacier, and balanced on the edge of the glacial outflow stream running at flood stage from the glacier. The wreckage was in an unstable location. The two occupants were removed from the airplane, initial documentation of the wreckage was performed by the NTSB IIC, and it was determined to be too hazardous an area to continue the investigation. About two hours later, prior to a helicopter recovery of the wreckage to a safe location for detailed inspection, the airplane was struck by a falling serac from the hanging glacier, and pushed into the glacial outflow. The initial documentation revealed the following: The fuselage came to rest inverted, with the nose pointed about 330 degrees magnetic, and facing uphill, in a rocky area of large granite boulders. No impact marks or debris were visible in the surrounding area, or on the face of the cliffs immediately above the wreckage site. A single, freshly broken tree was observed on a small ridge, 380 linear feet from the wreckage, on a bearing of 240 degrees magnetic. This tree was located at 950 feet msl. A freshly broken piece of tree was located on the open rocky slope, midway between, and on a direct line from, the tree to the wreckage. The line from the broken tree to the wreckage was 060 degrees magnetic. This direction is toward the eastern entrance of the valley, heading out of the pass. The valley was about two miles wide at the accident site. The compass card of the magnetic heading indicator in the cockpit was trapped in the indicator case, on a heading of 025 degrees magnetic. Both floats, wings, vertical and horizontal stabilizers, all flight control surfaces, and the engine, were located at the single impact site. All of these major components were still attached to each other. Both wings were broken aftward at the spar attachments. Both wing tanks were ruptured. Both wings had accordian type damage across the entire leading edge. The damage on the left wing leading edge could be matched to the adjacent boulders. No evidence of wood was observed in the leading edge of either main wing. The horizontal and vertical stabilizer leading edges appeared undamaged. The anti-collision beacon on top of the vertical fin was intact. The flaps were in the retracted position. The flap selector handle in the cockpit was broken from its mount, and the selected position could not be determined. Flight control cables were intact from both ailerons and flaps, to the fuselage center section. The airplane came to rest on top of the engine. The engine spinner was pointed 150 degrees magnetic (downhill). Two propeller blades were visible, with one having broken free of the hub. Both magnetos were visible, with their mounts broken free of the accessory section of the engine. The visible fractures were jagged and shiny. The mounting bolts appeared intact. The tips of both floats were deformed aft, and up, to the forward spreader bar. The IIC, an FAA airworthiness inspector, and a representative of Teledyne Continental Motors, returned to the accident site on October 29 to examine wreckage which became visible as the water flow in the glacier river receded. The engine, the tail cone section including the stabilizer trim actuators, and numerous small pieces of sheet metal were located in the river bed downstream of the original impact site. The engine was found at 420 feet msl, about 1/4 mile downstream of the initial impact site. The portions of wreckage located were fragmented. The left and right horizontal stabilizer trim actuators were extended to 8.0 inches, and 8.4 inches, respectively. This corresponds to a horizontal stabilizer trim setting between -2.8 degrees and -1.9 degrees, or slightly nose down from the "takeoff" neutral setting. Full nose up trim is -8.0 degrees, and full nose down trim is +1.0 degrees. The Continental Motors O-470K engine had a 12 inch hole in the top of the case. All six connecting rods were intact and straight. All six cylinders were intact and seated. No preaccident anomalies were visible on the pistons or valves. Both the crankshaft and camshaft were intact, with no evidence of heat damage. No accessories remained attached to the engine accessory case. The propeller flange was fractured, and the propeller attaching bolts were bent. The propeller flange fracture surfaces appeared jagged and shiny. MEDICAL AND PATHOLOGICAL A postmortem examination was performed on the pilot by the Alaska State Medical Examiner, 5700 East Tudor Avenue, Anchorage, Alaska, on August 9, 1999. The cause of death was noted to be multiple impact injuries sustained in the accident. Toxicological samples were tested at the FAA Civil Aeromedical Institute, Oklahoma City, Oklahoma, on September 8, 1999. No anomalies were noted. SURVIVAL ASPECTS The airplane's emergency locator transmitter (ELT) signal was first received by satellite before 1348 ADT. The exact time of the first signal receipt is not known. According to the duty officer at the Search And Rescue Satellite (SARSAT) coordination center at Langley Air Force Base, Virginia, at least two separate satellite positions must be received to generate a composite position, and the second pass was at least 40 minutes after the first. A composite position and alert was generated at 1438, and passed to the Air Force Alaskan Rescue Coordination Center in Anchorage, who initiated a search by the CAP. The CAP was unable to la
The pilot's intentional visual flight into known adverse weather. Factors associated with this accident were the reported low ceilings, obscuration, high winds, and turbulence.
Source: NTSB Aviation Accident Database
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