ANC16LA034

On June 19, 2016, about 1525 Alaska daylight time, a single-engine, turbine-powered, float-equipped de Havilland DHC-3T (Otter) airplane, N104BM, struck a Bald Eagle while en route 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) flight under the provisions of 14 Code of Federal Regulations Part 91 as a training flight. Visual meteorological conditions prevailed at the time of the accident, and company flight following procedures were in effect. The flight originated from 5BL, about 1520. The operator reported in a written statement submitted to the National Transportation Safety Board investigator-in-charge on June 20, that while on a company 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, and noted that the leading edge was damaged and deformed. The operator reported that the airplane was flying straight and level on a northeasterly heading, about 120 miles per hour (mph), and at an altitude of about 2,500 feet at the time of the impact. The flight crew notified the Homer Flight Service Station of the Bald Eagle strike and their intentions to return to 5BL. The operator reported that at this time, the airplane was flying normal with no control issues. However, the first attempt at landing was aborted due to an uncontrollable aileron roll to the left when the airspeed decayed below 75 mph. The flight crew declared an emergency and requested emergency services at 5BL. During the subsequent landing, the flight crew maintained the airspeed above 75 mph until an altitude that was just above the surface of the water. The landing was accomplished without any further control issues. The airplane sustained substantial damage to the left wing. Portions of the Bald Eagle remains were retrieved from inside the left wing and sent to the Smithsonian Institution Feather Identification Laboratory in Washington, D.C. The pilot reported there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. METEOROLOGICAL INFORMATION The closest official weather observation station is located at the Homer Airport (HOM), Homer, about 10 miles southwest of the accident site. At 1453, an Aviation Routine Weather Report (METAR) was reporting, and stated in part: wind 6 knots at 220 degrees; visibility 10 statute miles; clouds and sky condition, scattered clouds at 4,500 feet, overcast clouds at 6,000 feet; temperature 57 degrees F; dew point 48 degrees F; altimeter 29.92 inHg. WRECKAGE AND IMPACT INFORMATION The left wing sustained substantial damage to the leading edge, outboard of the landing light. The leading edgewas 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. The resulting hole in the wing appeared to be about 1 foot square. The airplane sustained an aerodynamic performance degradation at a slow airspeed, which is likely due to the drag created by the facture in the wing and the disruption of the air flow over the wing's surface. The operator reported that various skin panels along with 3 nose ribs were replaced to facilitate the repair of the left wing. TESTS AND RESEARCH The Smithsonian Institution Feather Identification Laboratory reported that the remains were positively identified as Bald Eagle (Haliaeetus leucocephalus). The identification was made using mtDNA (cytochrome oxidase 1) and confirmed with microscopic analysis. The Smithsonian Institution Feather Identification Laboratory further reported that the mass of the subspecies of Bald Eagle that occurs in Alaska ranges from 3637 grams to 4819 grams (mean 4130 grams) for adult males, and 4631 grams to 6400 grams (mean 5350 grams) for adult females. ADDITIONAL INFORMATION Bald Eagle Range and Habitat The Alaska Department of Fish and Game has published the Bald Eagle Profile (2016). This document discusses the range and habitat of the Bald Eagle in Alaska and states in part: Alaska has the largest population of Bald Eagles in the United States, about 30,000 birds. Bald Eagles are often found along Alaska's coast, offshore islands, and interior lakes and rivers. Most Bald Eagles winter in southern Alaska but some leave the state during cold months. The highest nesting densities occur on the islands of Southeast Alaska where Bald Eagles usually nest in old-growth timber along saltwater shorelines and mainland rivers. Bald Eagles in Southcentral Alaska nest in old cottonwood trees near water. Bird Strike Avoidance The Aircraft Owners and Pilots Association (AOPA) Air Safety Institute has published Heard About The Bird? (2000). This document discusses guidance for avoiding bird strikes and states in part: Avoid low altitude flight as much as feasible to reduce the risk of a strike. Dawn and dusk are the times with the highest probability of a bird encounter. Turn on landing or recognition lights. This helps birds see oncoming aircraft. Plan to climb. Birds almost invariably dive away, but there are exceptions. Slow down. This will allow birds more time to get out of your way and will lessen the impact force if you do hit one. If a collision seems likely, duck below the glareshield to avoid being hit by the bird and flying plexiglass. Advise passengers to do the same. Protect your eyes and head. If a collision occurs, fly the aircraft first. Assess the damage and decide whether you can make it to an airport or you should make an off-airport landing. Declare an emergency - it doesn't cost anything. Even if no damage isvisible, divert to the nearest airport and have a mechanic look at the airplane.