SEA05LA133
SEA05LA133

On October 19, 2004, about 1200 Pacific daylight time, an Aero Vodochody L-39C, N39TJ, collided with mountainous terrain about seven miles east of Hyak, Washington, after radio and radar contact were lost at 1158. The 14 CFR Part 91 personal pleasure flight, which departed Boeing Field, Seattle, Washington, at 1146, was in an area of reported instrument meteorological conditions (IMC), and the pilot had activated his previously filed Instrument Flight Rules (IFR) flight plan. No ELT signal has been detected in the area where radar contact was lost, and the search for the aircraft was called off six days after the aircraft went missing (10/25/04). The jet aircraft, which had been issued an experimental-exhibition airworthiness certificate, was eventually located in the third week of June 2005, when some hikers came across the remains of the wreckage. About a week after they discovered the scene, the hikers realized that what they found may have been a previously undiscovered missing aircraft, so they reported their find to the FAA. Both occupants, a private pilot and his passenger, received fatal injuries, and the aircraft had been destroyed.

On the day of the accident, approximately nine minutes after takeoff, the aircraft was passed from Seattle Approach Control to Seattle Center. At that time, the pilot reported that he was passing 8,000 feet for 15,000 feet. About 70 seconds later, the center controller asked the pilot if he would prefer to climb to 15,000 feet or 17,000 feet, and the pilot responded with 17,000 feet. He was then cleared to 17,000 feet by the controller. About one minute later, the pilot was given a clearance to proceed direct to Lewiston, Idaho. At that time he gave no indication of having encountered any problem. Then about five seconds after being cleared to Lewiston, the pilot advised Center that he had a flight control problem, and about ten seconds after that, he stated that he had an in-flight emergency. About fifteen seconds after declaring the emergency, the pilot transmitted three times in a rapid excited voice that he was "out of control." The controller was not able to make any further radio contact with the aircraft.

A preliminary review of recorded radar tracking data (NTAP) indicates that the aircraft climbed to a mode C altitude of 17,100 feet, but was there for less than 15 seconds before starting to descend again. The aircraft was lost from radar just over one minute after it reached 17,100 feet (at 11:58:03), and at the time was approximately 15,900 feet. At the time it was lost from radar, its geographic location was 47 degrees, 21 minutes, 41.8 seconds North, and 121 degrees, 16 minutes, 38.7 seconds West. The aircraft wreckage was eventually found at 47 degrees, 22 minutes, 38.9 seconds North, and 121 degrees, 16 minutes, 7.76 seconds West.

The aircraft's initial impact with the terrain was through the trunks of two mature conifer trees, and a line drawn from those points of impact to the ground impact crater was approximately 70 degrees above the horizontal plane. The impact crater itself was about 10 feet wide and 14 feet long, and was approximately five feet deep at its center. Mounds of dirt had been pushed up around the perimeter of the crater by the force of the impact, and small pieces of wreckage were scattered up to one-eighth mile to each side of the crater, and up to one-half mile out along the longitudinal axis of the crater. Except for portions of the engine, landing gear, and vertical stabilizer, the entire aircraft had been torn into numerous small pieces, most of which were hard to identify due to the extent of the damage they suffered during the impact sequence. According to the recovery team, which worked for three days in the mountainous terrain cleaning up the scattered wreckage, there were over 1,000 separate pieces of the aircraft recovered.

Although four small pieces of what appeared to be flight control surfaces were identified, due to the extent of the damage, no determination as to the integrity of the flight controls, or the functionality of the flight control system could be made. An inspection of the engine revealed that the majority of the compressor blades had either been bent 45 degrees or more in a direction opposite that of normal engine rotation, or had been broken off at their base. Many of the turbine blade tips had been ground down where they had made rotational contact with the outer wall of the turbine section, and many of both the compressor and turbine blades showed extensive foreign object damage on their leading edges.

Although there was an AIRMET (Airman's Meteorological Information) in effect for the general area of the flight that called for the possibility of occasional moderate rime and mixed icing in clouds and precipitation from the freezing level up to flight level 200, the pilot did not make any mention to the controller of the accumulation of ice on the aircraft, and the last PIREP (Pilot Weather Report) mentioning icing in the area (trace amount) was over two hours prior to the accident.





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