Accident Details
On June 19, 2016, at approximately 1525 Alaska daylight time, a single-engine, turbine-powered, float-equipped de Havilland DHC-3T (Otter) airplane, registration N104BM, struck a Bald Eagle while en route at about 2,500 feet and 10 miles northeast of the Homer-Beluga Lake Seaplane Base (5BL), Homer, Alaska. The two airline transport pilots sustained no injuries, and the airplane sustained substantial damage. The airplane was registered to a private individual and operated by Bald Mountain Air Services, Inc., Homer, as a visual flight rules (VFR) training flight under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The flight originated from 5BL about 1520.
The operator reported that during the training flight, the flight crew observed what they believed to be a Bald Eagle immediately before hearing and feeling an impact to the left wing, noting damage and deformation to the leading edge. At the time of impact, the airplane was flying straight and level on a northeasterly heading at about 120 miles per hour (mph) and an altitude of about 2,500 feet. The flight crew notified the Homer Flight Service Station of the strike and their intention to return to 5BL. The airplane initially flew normally with no control issues; however, the first landing attempt was aborted due to an uncontrollable aileron roll to the left when airspeed decayed below 75 mph. The flight crew declared an emergency and requested emergency services at 5BL. During the subsequent landing, they maintained airspeed above 75 mph until just above the water surface, and the landing was accomplished without further control issues.
The pilot reported no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.
Wreckage and Impact
The left wing sustained substantial damage to the leading edge, outboard of the landing light. The leading edge was damaged and deformed over a spanwise length of about 3 feet. The leading edge, upper wing skin, and lower wing skin were also fractured at the impact point. The fracture in the upper wing skin extended aft about 2 to 3 feet, resulting in a hole approximately 1 foot square. The operator reported that the airplane experienced aerodynamic performance degradation at slow airspeed, likely due to drag from the fracture and disrupted airflow over the wing's surface. Various skin panels along with 3 nose ribs were replaced to facilitate repair.
Meteorological Information
The closest official weather observation station was at Homer Airport (HOM), about 10 miles southwest of the accident site. At 1453, an Aviation Routine Weather Report (METAR) reported: wind 6 knots at 220 degrees; visibility 10 statute miles; scattered clouds at 4,500 feet, overcast clouds at 6,000 feet; temperature 57°F; dew point 48°F; altimeter 29.92 inHg.
Tests and Research
The Smithsonian Institution Feather Identification Laboratory positively identified the bird remains as a Bald Eagle (Haliaeetus leucocephalus) using mtDNA (cytochrome oxidase 1) and confirmed with microscopic analysis. The laboratory reported that the mass of the subspecies of Bald Eagle occurring in Alaska ranges from 3,637 to 4,819 grams (mean 4,130 grams) for adult males and 4,631 to 6,400 grams (mean 5,350 grams) for adult females. Portions of the eagle remains were retrieved from inside the left wing.
Additional Information
The Alaska Department of Fish and Game's Bald Eagle Profile (2016) notes that Alaska has the largest Bald Eagle population in the United States, about 30,000 birds, often found along coasts, offshore islands, and interior lakes and rivers. Most winter in southern Alaska. Highest nesting densities occur on Southeast Alaska islands, and in Southcentral Alaska they nest in old cottonwood trees near water.
The Aircraft Owners and Pilots Association (AOPA) Air Safety Institute's publication "Heard About The Bird?" (2000) provides guidance for avoiding bird strikes, including avoiding low altitude flight, turning on lights, planning to climb, slowing down, and ducking below the glareshield if a collision is imminent. After a strike, pilots should fly the aircraft first, assess damage, and declare an emergency.