Accident Overview
On September 25, 2022, at approximately 1300 Alaska daylight time, a Cessna 180A floatplane, registration N9728B, was involved in an accident on Whiskey Lake near Skwentna, Alaska. The pilot was fatally injured. The aircraft was substantially damaged. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
According to a family member, the pilot sent a text message at 1240 indicating she was ready to taxi for departure from Whiskey Lake. The intended destination was Lake Hood (PALH) in Anchorage, Alaska. The family member estimated a 45-minute flight time. When the aircraft was about 15 minutes overdue, they began making inquiries. A friend flew over Whiskey Lake and spotted a submerged airplane.
Members of the Alaska State Troopers (AST) Search and Rescue team located the airplane and pilot at about 1630. Initial photographs showed the left float had separated from the aircraft and was found approximately 175 yards from the main wreckage. The right float remained partially attached to the submerged wreckage. On October 4, 2022, the Alaska Dive Search Rescue and Recovery Team recovered the aircraft from the lake and moved it to the shoreline.
Aircraft Information
The aircraft was a Cessna 180A equipped with EDO 249-2870 floats. According to airworthiness records, the floats were installed in June 1960. No maintenance records were available for review. The pilot's logbooks were not located.
Wreckage Examination
On October 6, 2022, the National Transportation Safety Board investigator-in-charge, along with representatives from Cessna Aircraft and the Federal Aviation Administration, examined the wreckage. Flight control cable continuity was established from controls to control surfaces. The right wing was damaged from the tip inward; the wing tip was not located. The left wing remained submerged. The water rudder handle was in the UP position, and the flaps were retracted. The propeller remained attached to the engine crankshaft flange, with one blade curled aft at the tip and the other bent aft at midspan. Damage consistent with propeller strikes was noted on the inboard portion of the right float.
The bottoms of both floats were heavily corroded and discolored. The right float remained attached to the airframe by the fly wire. Six patches of varying size were noted on the right float hull. A portion of the float hull, about midspan from the tip to the step, was partially separated and bent aft. No evidence of impact with a foreign object was observed. The left float had impact damage at the front tip and one patch on the hull, with another patch on top of it.
Medical and Pathological Information
An autopsy performed by the Alaska State Medical Examiner’s Office determined the cause of death as blunt force injuries and subsequent drowning. Toxicology testing by the FAA’s Bioaeronautical Sciences Laboratory detected diazepam (12 ng/mL) and its metabolite nordiazepam (9 ng/mL) in femoral blood. Venlafaxine and its metabolites were detected at 18 ng/mL and 112 ng/mL, respectively. Metoprolol and timolol were detected in liver tissue; metoprolol was also found in femoral blood, while timolol results were inconclusive. Diazepam is a prescription benzodiazepine with sedative effects that can impair cognitive and psychomotor performance; the FAA considers an open prescription for diazepam disqualifying for medical certification.