N665SPCessna 172S · 1998

On February 15, 2012, about 0154 Pacific standard time, a Cessna 172S, N665SP, was substantially damaged following impact with terrain on the western face of Mount Si, near North Bend, Washington. The airplane was registered to Christiansen Aviation Inc., Wilmington, Delaware, and operated by the pilot, under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91. The commercial pilot and his two passengers sustained fatal injuries. Dark night visual meteorological conditions prevailed and no flight plan was filed for the personal flight. The local flight originated from the Renton Municipal Airport (RNT), Renton, Washington, at 0135.

A witness, who was a rated private pilot, reported that while driving in an easterly direction on Interstate 90 (I-90), he observed anti-collision and navigation lights from a low flying airplane that was flying in a southeasterly direction, about 1 mile north of I-90. The witness stated that as I-90 turned to a southwesterly direction, he lost sight of the airplane for a couple of minutes, however, reestablished visual contact with the airplane as he and the airplane approached North Bend. The witness said that at that time, the airplane altered its course and was traveling in a northeasterly direction at an estimated altitude of about 1,000 feet above ground level (agl). The witness added that visibility was at least 3 miles with a high overcast cloud ceiling and a few lower elevation clouds.

Several witnesses located near the accident site reported having heard an impact sound. One witness reported observing the lights of a low flying airplane over his location about 300 to 500 feet agl. The witness stated that he heard the engine rev up and couldn’t see the lights anymore. Shortly thereafter, they heard a pop along with the engine noise suddenly stop.

A review of Federal Aviation Administration (FAA) recorded radar data revealed that the accident airplane was on initial climb from RNT. The airplane ascended to an altitude of about 2,400 feet mean sea level (msl), initially traveling in a northeasterly direction. As the airplane approached the area of Snoqualmie Falls, it descended to an altitude of about 1,500 feet msl, and traveled along an east-southeasterly course. The last recorded radar target was at 0146, about 1.5 miles southwest of Snoqualmie Falls at an altitude of 1,500 feet msl. The last radar target was located about 6.11 miles northwest of the accident site.

According to one of the passenger’s family members, the pilot and the two passengers attended a local hockey game that started at 1930. Following the game, the pilot and passengers went to dinner.

The pilot, age 30, held a commercial pilot certificate with airplane single-engine land, airplane multi-engine land, and instrument airplane ratings. The pilot also held a flight instructor certificate with airplane single-engine land, airplane multi-engine land, and instrument airplane ratings. A first-class airman medical certificate was issued to the pilot on August 8, 2007, with no limitations stated. Review of the pilot’s logbook revealed that as of the most current logbook entry, dated February 12, 2012, he had accumulated 991.5 hours of total flight time.

The four-seat, high-wing, fixed-gear airplane, serial number (S/N) 172S8069, was manufactured in 1998. It was powered by a Lycoming IO-360-L2A engine, serial number L-27912-51A, rated at 180 horsepower. The airplane was also equipped with a McCauley 1A170E/JHA7660, serial number SH101, fixed pitch propeller. Review of the aircraft maintenance records revealed that the most recent annual inspection was completed on October 10, 2011, at an airframe total time of 5,477.3 hours and engine time since major overhaul of 560.7 hours.

A review of recorded data from the Renton Municipal Airport automated weather observation station, located 21 miles east of the accident site, revealed at 0756, conditions were wind from 160 degrees at 5 knots, visibility 6 miles, mist, few clouds at 2,800 feet, overcast cloud layer at 4,000 feet, temperature 2 degrees Celsius, dew point 2 degrees Celsius, and an altimeter setting of 30.25 inches of mercury.

Examination of the accident site revealed that the airplane impacted trees and terrain on an approximate heading of about 120 degrees magnetic at an elevation of about 1,958 feet msl. Multiple topped trees and damaged tree limbs were noted within the wreckage debris path. Both wings, horizontal, and vertical stabilizers were separated and located throughout the wreckage debris path. The fuselage came to rest inverted and the engine remained attached.

Partial flight control cable continuity was established due to the extent of impact damage to the aircraft. The rudder flight control cables remained attached to the control horn at the tail of the aircraft. The ailerons and flap control cables were observed with tension overload separations at the inboard section of each wing and remained attached to the flight controls. The flap actuator was observed with no threads exposed corresponding to a 0 degree flap setting. The elevator control cables were observed with tension overload separations consistent with the separation of the horizontal stabilizer surfaces. The elevator trim tab control cables and actuator remained attached to the tail. The elevator trim actuator was measured and found to be 1.3 inches, which equated to a neutral trim position.

The top spark plug for the number 2 cylinder was removed and exhibited normal wear signatures as per the Champion Aviation Check-a-Plug chart. The fuel distribution valve was opened and observed with no debris or damage to the diaphragm. The propeller was separated from the crankshaft and exhibited leading edge polishing and “S” bending.

The on-site examination of the airframe and engine, revealed no evidence of a mechanical malfunction or failure with the airframe or engine prior to impact. The wreckage was not recovered from the accident site.

The King County Medical Examiner conducted an autopsy of the pilot on February 16, 2012. The medical examiner determined that the cause of death was “...blunt force trauma...”

The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on the pilot. According to CAMI's report, carbon monoxide, cyanide, volatiles, and drugs were tested, and had positive results for 246 (mg/dL, mg/hg) Ethanol detected in the Urine, 195 (mg/dL, mg/hg) Ethanol detected in the Vitreous, 154 (mg/dL, mg/hg) Ethanol detected in the blood, 92.08 (ug/ml, ug/g) Acetaminophen detected in the urine, 6.852 (ug/ml, ug/g) Dipehnhydramine detected in the blood, and an unspecified amount of Dipehnhydramine in the urine and liver.

Information obtained from CAMI revealed, “…ethanol is primarily a social drug with a powerful central nervous system depressant. After absorption, ethanol is uniformly distributed throughout all tissues and body fluids. The distribution pattern parallels the water content and blood supply of each organ. Postmortem production of ethanol also takes place due to putrefaction processes, but vitreous humor and urine do not suffer from such production to any significant extent in relation to blood. Vitreous humor would normally have about 12% more ethanol than blood if the system is in the post absorptive state, and urine would normally have about 25% more ethanol than blood. The average rate of elimination of ethanol from blood is 18 mg/dL (15-20 mg/dL) per hour.”

CAMI also states that Title 14 CFR 91.17 (a) “prohibits any person from acting or attempting to act as a crewmember of a civil aircraft while having 0.040 g/dL (40.0 mg/dL) or more alcohol in the blood.” Adverse clinical symptoms have been noted with blood ethanol levels as low as 20.0 mg/dL (0.020 g/dL).”