BOULDER, CO, USA
N6505L
Grumman American AA-1B
Numerous witnesses at about 7,000 feet elevation observed the airplane flying at low altitude in mountainous terrain. The airplane struck power lines and trees while attempting to climb through a steep narrow canyon. The pilot possessed a student pilot certificate and was carrying his son as a passenger. He had recently moved to Colorado from Long Island, New York. The pilot's flight instructor, who had ferried the airplane from Long Island to Colorado, cautioned him that his airplane 'was not good for Colorado' because it was underpowered. The instructor also 'strongly encouraged' the pilot to get a mountain checkout. A low level of tetrahydrocannabinol carboxylic acid (active metabolite of marijuana) was detected in the pilot's blood. The same substance was detected in the passenger's urine.
HISTORY OF FLIGHT On August 20, 1996, approximately 1310 mountain daylight time, a Grumman American AA-1B, N6505L, collided with trees while climbing and impacted terrain near Boulder, Colorado. The student pilot and passenger were fatally injured and the airplane was destroyed by the impact and a post crash fire. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight conducted under Title 14 CFR Part 91. The local flight originated at Boulder, Colorado, on August 20, 1996, approximately 1000. The Boulder County Sheriff's Office received the first call of a downed airplane approximately 1315. Witnesses reported seeing an airplane matching the description of N6505L prior to the accident (see "Witness Location Map" attached). Witness No. 1 was hiking on Green Mountain approximately the 7,000 to 7,100 foot level. He said the airplane "flew into view from the front (east side) of Green Mountain. The plane proceeded, at an elevation below my position, to fly up Gregory Canyon into the mountains. The plane turned to the north behind Flagstaff Mountain and disappeared below the horizon into Boulder Canyon...The plane that crashed was flying into a headwind at or slightly below the elevation of Flagstaff Mountain (elevation 6,960 feet). I lost sight of the plane when it entered Boulder Canyon...My elevation was above that of Flagstaff (Mountain), so the plane would have to have been down in Boulder Canyon...The plane that crashed was very low...There was no indication of engine trouble or of any other trouble with the flight." Witness No. 2, who was on Flagstaff Mountain's Range View Trail at the 6,800 foot level, "saw plane fly by at eye level...going west-northwest over Gregory. Plane made no unusual noises." Witness No. 3, who was working on Fourmile Canyon Road, said he saw "a small, blue, single engine airplane flying in the area. There was nothing unusual about its flight...heading west, normal attitude, at an altitude of about 500 to 1,000 feet above the nearest mountain top." Two other witnesses reported seeing the airplane crash. Witness No. 4 was riding her bicycle up Fourmile Canyon Road when she heard a "strange" noise, then a loud engine sound above her. She saw an airplane cross 50 feet overhead and 150 feet in front of her, traveling east to west. The engine sounded like it was running. The airplane was traveling parallel to the ground rather than nosediving when it collided with trees below the power lines alongside the road. Witness No. 5, a 9 year old girl in a nearby cabin, saw "a blue plane out the top window of the cabin with its wings wobbling." Other nearby residents reported power and telephone outages. It was later discovered three service lines adjacent to the accident site had been severed. PERSONNEL INFORMATION The pilot's flight log was not located. According to FAA records, he held a combination Student Pilot/Third Class Medical Certificate No. EE-1211522, dated January 5, 1996. At the time of certificate application, the pilot indicated he had accrued 330 flight hours, of which 120 hours were accumulated within the previous six months. The pilot's flight instructor confirmed he had only a student pilot certificate, but added he was "close to the checkride." At the pilot's request, the instructor ferried N6505L from Brookhaven, New York, to Colorado. Upon arrival in Boulder, the instructor cautioned the pilot that his airplane "was not good for Colorado" because it was underpowered. He suggested that the pilot sell the airplane and purchase "something bigger." He told the pilot to get his pilot's license, and "strongly encouraged" him to get a mountain checkout. AIRCRAFT INFORMATION The airplane maintenance records were not located. The airplane had previously been based at Brookhaven (Calabro) Airport in Shirley, New York. According to an airplane maintenance facility owner at that airport, he had performed the last two annual inspections on N6505L. The first inspection was performed on August 1, 1996, at a recording tachometer time of 1829 hours (775 hours since engine top overhaul), and the second inspection was accomplished on August 8, 1995, at 1805 hours, a difference of 24 hours in the 12 month period. The airplane was blue with white trim. According to FAA records, the airplane was registered to the pilot on November 22, 1993. WRECKAGE AND IMPACT INFORMATION The wreckage was at a location of 40o02'30"N and 105o28'00"W. Examination of the accident site disclosed a 50-foot swath of severed tree tops aligned on a magnetic heading of 330 degrees. Adjacent to the beginning of the swath were three downed telephone and power lines. According to the power company repairman, the circuit breaker on the power pole tripped, but the time of the power outage was not recorded. The swath terminated at a creek bed containing the burnt wreckage of N6505L. All of the wreckage was contained within a 150 square foot area at the creek bed. All major components were accounted. The rudder remained attached to the vertical stabilizer and the elevators remained attached to the horizontal stabilizers. The fuselage, both wings, flaps, and ailerons were destroyed by the ensuing fire, negating any evidence of fuel quantity aboard the airplane. Rudder, elevator, and aileron control cables were identified and control continuity was established to the cockpit area; thereafter, continuity was destroyed by the post-impact fire. The flap actuator rod was identified, and measurements taken indicated the flaps were up. Cockpit instruments indications and switch positions could not be documented due to fire damage. The descending propeller blade was bent aft slightly approximately midspan. The cambered surface bore 45 degree scratch marks. The trailing edge was gouged near the tip. The ascending propeller blade was severed approximately six inches from the hub, and was bent slightly aft. The engine was intact but had been exposed to the ground fire. Coked oil was found on the dip stick. MEDICAL AND PATHOLOGICAL INFORMATION Autopsies were performed on both the pilot (#96A-93) and passenger (#96A-94) by Dr. Brooke Alt for the Boulder County Coroner's Office. Also performed was a toxicology screen on passenger specimens. The passenger tested "high positive" for Tetrahydrocannabinol (THC, or Marijuana). Toxicology protocol was performed on pilot specimens by FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma. According to its report (#9600219001), the pilot tested positive for Tetrahydrocannabinol (THC, or Marijuana). Blood samples revealed 0.003 ug/ml in blood, and urine samples revealed 0.102 ug/ml. According to a CAMI physician/toxicologist, THC acts as a depressant and the level detected in the pilot's blood was "significant." ADDITIONAL INFORMATION The wreckage was released to the custody of Beegles Aircraft Service, Inc., Greeley, Colorado, on August 21, 1996.
The pilot's poor judgment in attempting low altitude flight in mountainous terrain without adequate mountain flying training which led to low altitude maneuvering exceeding the climb capability of the airplane. Factors in the accident were: the pilot's overconfidence in his personal ability, lack of experience in flying in mountainous terrain, lack of familiarity with the geographic area, and the mountainous and canyon-featured terrain.
Source: NTSB Aviation Accident Database
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