The pilot of the de Havilland DHC-3 Otter floatplane that crashed last month in Washington state was trying to avoid inclement weather, according to a preliminary report released by the National Transportation Safety Board (NTSB).
The accident took place on July 23, around 5:20 p.m. local time near Eastsound. The aircraft, N709KA, was substantially damaged and the pilot and two passengers were seriously injured. Eight passengers sustained minor injuries in the crash. The airplane was operated by Kenmore Air as a Part 135 scheduled air taxi flight.
Per the NTSB, the operator reported the flight originated from Kenmore Sea Base (W55), Seattle, at 4:30 p.m. local time with scheduled stops at Roche Harbor (WA03) and Friday Harbor (W33) in Washington.
According to preliminary ADS-B data, the aircraft flew at an altitude of 500 to 1,000 msl over the water as it headed north over the Rosario Strait. When northwest of Lummi Island, the airplane turned west and passed north of Sucia Island.
At this time the pilot radioed the operator at the base at Kenmore to report inclement weather, which precluded the flight from continuing to Roche Harbor. The pilot stated he would return to Sucia Island and land to wait for the weather to improve. According to the operator, there were multiple bays around Sucia Island where the pilot was authorized to land.
According to ADS-B data, at approximately 4:19 p.m. the airplane was about 11 miles northeast of Roche Harbor when it turned to a heading of 180° and flew towards Sucia Island, which was approximately 5 miles away.
Video shot by a witness near Shallow Bay, Sucia Island, shows the aircraft a few feet over the water in a nose-high attitude as it descends. Per the NTSB report, “When the airplane was about 4 ft above the water, the left wing dropped and the left wingtip and left pontoon float impacted the water. The airplane then landed with both pontoon floats on the water and continued forward where it subsequently impacted rocks.”
Chapter 3 of the FAA’s manual on seaplanes (FAA-H-8083-23-2) notes many of the operational differences between land planes and seaplanes relate to the fact that seaplanes have no brakes. The text goes on to note, “The seaplane continues moving after the engine is shut down, and this energy, along with the forces of wind and current, is typically used to coast the seaplane to the desired docking point.”
The day of the accident the Otter struck the rocks hard. Several small boats arrived immediately to remove passengers from the aircraft.
The aircraft subsequently caught fire after the passengers had exited. The wreckage was recovered and moved to a secure hangar for further examination.
The NTSB’s final report is likely 18 months to two years away.