ANC16FA019

The purpose of the flight was to conduct low-level aerial surveying and photography. A review of Federal Aviation Administration air traffic radar data revealed that the airplane departed the airport in a southerly direction before turning west and then conducted two 360° turns. The airplane then proceeded northeast of the airport for about 4 miles before turning toward the southwest, overflying the intended photography area and continuing past Beach Lake. The airplane then turned east for about 2 miles before the radar track terminated. The airplane was found in a densely wooded area, and a postcrash fire ensued, which consumed a majority of the fuselage. Examination of the wreckage revealed upward and aft crushing of the leading edge of the left horizontal stabilizer, and no scratching or gouging was found, consistent with an in-flight impact with a soft-bodied object. An examination of a complete feather found near the first pieces of debris and samples of organic material that contained several microscopic feather barbs and barbules taken from the left side of the airplane's fuselage and the tail section revealed that they were consistent with that of a Bald Eagle. Given this evidence, it is likely that the airplane impacted one or more eagles in flight and that the pilot subsequently lost airplane control.

The airplane was manufactured in 1981. It was equipped with a Lycoming O-320 series engine. The last annual inspection was completed on June 2, 2015, at which time the airplane had 19,660 hours in service. On April 20, 2016, about 0900 Alaska daylight time, a Cessna 172 airplane, N63541, impacted birds in flight and then terrain about 2 miles southwest of Birchwood Airport (BCV), Chugiak, Alaska. The airline transport pilot and three passengers sustained fatal injuries. The airplane sustained substantial damage. The airplane was registered to the pilot and was being operated by 70 North LLC, Anchorage, Alaska, as a 14 Code of Federal Regulations Part 91 visual flight rules aerial photography flight. Visual meteorological conditions existed near the accident site at the time of the accident, and company flight-following procedures were in effect. The purpose of the flight was to conduct aerial surveying and photography over an area of land adjacent to the west edge of the airport property. A review of Federal Aviation Administration (FAA) air traffic radar data revealed that the airplane departed BCV about 0840 in a southerly direction before turning west and then conducted two 360° turns. The airplane then proceeded northeast of BCV for about 4 miles before turning toward the southwest, overflying the intended photography area and continuing past Beach Lake. The airplane then turned east for about 2 miles before the radar track terminated. The last radar point indicated that the airplane was about 800 ft mean sea level (msl) and 102 knots and traveling on about a 126° ground track. The Alaska State Medical Examiner, Anchorage, Alaska, conducted an autopsy of the pilot on April 21, 2016. The cause of death for the pilot was attributed to "multiple blunt force injuries." The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicology testing on specimens from the pilot. The testing was negative for ethanol, drugs, and carbon monoxide. The closest weather reporting facility was BCV, about 2 miles northeast of the accident site. At 0806, a BCV METAR reported, in part, wind calm; sky condition, overcast clouds at 8,000 ft; visibility 9 statute miles; temperature 39°F; dew point 30°F; and altimeter setting 30.04 inches of mercury. The pilot held an airline transport pilot certificate with airplane single-engine land, multiengine land, single-engine sea, helicopter, and instrument ratings. He also held a flight instructor certificate with airplane single-engine, airplane multiengine, helicopter, instrument airplane, and instrument helicopter ratings. His most recent FAA second-class medical certificate was issued on June 23, 2015, and with the limitation that he "must have available glasses for near vision. Not valid for any class after." The pilot's personal logbooks were not located. A review of company records revealed that, on a pilot history form dated April 19, 2016, the pilot indicated that his total flightexperience was about 11,700 hours, 180 hours of which were in the previous 12 months. Feather Identification A complete feather found near the first pieces of debris and samples of the organic material found along the left side of the fuselage, left horizontal stabilizer, vertical stabilizer, rudder, and elevator were sent to the Smithsonian National Museum of Natural History Feather Identification Lab, Washington, DC, for analysis. The complete feather perfectly matched a museum specimen of an immature, plumaged Bald Eagle. The organic material samples contained several microscopic feather barbs and barbules that were microscopically compared to all possible bird species in Alaska with similar feather structures. The samples matched the Bald Eagle in barbule length, pigmentation patterns, and node morphology. According to the US Department of Agriculture and the Smithsonian Institution, this is the first known and recorded Bald Eagle impact with an airplane in the United States that resulted in occupant fatalities. Engine Examination A follow-up examination of the engine and fuel system did not reveal any anomalies, contamination, or evidence of malfunction in any of the engine accessories. Examination of the cylinders, pistons, valve train, crankshaft, and other internal components revealed no evidence of an anomaly or malfunction that would have precluded normal operation. The magnetos remained secure at their respective mounting pad. The magnetos had sustained varying degrees of thermal damage that rendered the units inoperative; therefore, they could not be functionally tested. Magneto-to-engine timing could not be determined. Each of the magneto drives remained intact and undamaged. No evidence of impact with foreign objects was observed in the air passages and induction system of the carburetor and engine. The wreckage was located in a forested area of densely populated spruce and birch trees with thick underbrush at an elevation of about 230 ft msl. The distance from the initial impact point of an estimated 100-ft-tall spruce tree to the final piece of debris was about 160 yards along a magnetic heading of about 275°. Following the impact, a postcrash fire ensued, which consumed the fuselage. Flight control continuity was established from the cockpit controls to all control surfaces. The left horizontal stabilizer exhibited leading-edge crushing upward and aft toward the front spar. The rudder remained attached to the vertical stabilizer at the middle and upper attachment points. The rudder was bent upward and to the right about 100° at the middle attachment point. Organic material was present on the left side of the fuselage, vertical stabilizer, horizontal stabilizer, rudder, and elevator.