# NTSB ANC22LA080: Cessna 180A, N9728B, Skwentna, AK, September 25, 2022 - Type: NTSB accident investigation - Classification: Accident · Fatal · Class 3 · Limited · Final report - Date: September 25, 2022, 13:00 local (21:00 UTC) - Place: Skwentna, AK · Whiskey Lake - Coordinates: 61.991057, -151.40254 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=61.9911&lon=-151.4025&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Alaska Regional Office - Parties: Textron, FAA/FSDO - NTSB case key (mKey): 105993 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC22LA080 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/105993/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=105993 - Page: https://openairdocs.org/ntsb/ANC22LA080 ## Probable cause The failure of the landing gear float due to inadequate maintenance of the floats and corrosion. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: wheel/ski/float](https://openairdocs.org/ntsb-findings/01023246): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Pilot ## Analysis The pilot was departing on a cross-country flight in a float-equipped airplane when the accident occurred. She had contacted a family member and stated she was departing; however, she did not arrive at the destination when expected. A search was initiated, and the airplane was located partially submerged in the departure lake. Postaccident examination of the wreckage revealed that both floats were heavily corroded and separated from the fuselage. There was no evidence that either float had contacted a foreign object in the water. A portion of the hull on the right float tore open and bent back. It is likely that tear in the float resulted in the airplane impacting the water during the takeoff. Maintenance records were not available for review during the investigation. Though toxicology testing of the pilot’s tissue detected diazepam and venlafaxine and their metabolites in the pilot’s system, it is unlikely that the effects of these medications contributed to this accident. ## Factual narrative On September 25, 2022, about 1300 Alaska daylight time, a float-equipped Cessna 180A airplane, N9728B, was substantially damaged when it was involved in an accident near Skwentna, Alaska. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to a family member, the pilot sent a text message at 1240 indicating that she was ready to taxi for departure from Whiskey Lake so the family member would know when to expect her arrival. The intended route of flight was from Whiskey Lake to Lake Hood (PALH), Anchorage, Alaska. The family member estimated that it would take about 45 minutes to get from the departure point to the destination, and when the airplane was about 15 minutes overdue, he started calling around. A friend of the family flew over Whiskey Lake and found an airplane submerged in the water. Members from the Alaska State Troopers (AST) Search and Rescue team located the airplane and pilot about 1630. Initial on scene photographs taken by AST indicated that the left float separated from the airplane, and it was subsequently located about 175 yards away from the main wreckage. The right float remained partially attached to the submerged airplane wreckage. On October 4, 2022, members from the Alaska Dive Search Rescue and Recovery Team traveled to Whiskey Lake and recovered the submerged airplane, then moved it to the shoreline. PERSONNEL INFORMATION The pilot’s logbooks were not located. AIRCRAFT INFORMATION According to airworthiness records the floats were installed in June 1960. There were no maintenance records available for review. WRECKAGE AND IMPACT INFORMATION On October 6, 2022, the National Transportation Safety Board investigator-in-charge, along with representatives from Cessna Aircraft and the Federal Aviation Administration, traveled to the accident site. During the on-scene wreckage examination, flight control cable continuity was established from the control inputs to the control surfaces. The right wing was damaged from the tip of the wing inward; the wing tip was not located. The left wing remained submerged. The water rudder handle was in the UP position; the flaps were retracted. The propeller remained attached to the engine crankshaft flange. One blade was curled aft at the tip; the second blade was 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. There were six patches of varying size noted on the hull of the right float. A portion of the float hull, about midspan from the tip of the float to the step, was partially separated and bent aft. No evidence of impact with a foreign object was noted. (See Figure 1.) Figure 1 View of partially separated section on hull of the right float. The left float separated and was also recovered to the shore. Impactdamage was noted on the front tip of the float. There was one patch on the hull of the left float, with another patch on top of it. The aircraft was equipped with EDO 249-2870 floats. According to airworthiness records the floats were installed in June 1960. There were no maintenance records available for review. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy of the pilot was performed by the Alaska State Medical Examiner’s Office, Anchorage, Alaska. The cause of death was blunt force injuries and subsequent drowning. Toxicology testing performed by the Federal Aviation Administration’s (FAA) Bioaeronautical Sciences Laboratory detected diazepam in the pilot’s femoral blood at 12 ng/mL and the diazepam metabolite nordiazepam at 9 ng/mL in femoral blood. Venlafaxine and its metabolites were detected in femoral blood at 18ng/mL and 112 ng/mL, respectively. The high blood pressure medications metoprolol and timolol were detected in the pilot’s liver tissue; metoprolol was also detected in her femoral blood, while the result for timolol in her femoral blood was inconclusive. Diazepam, sometimes marketed as Valium, is a prescription benzodiazepine medication that can be used to treat a variety of conditions, including anxiety, muscle spasms, alcohol withdrawal, and seizures. Diazepam has sedative effects and can impair cognitive and psychomotor performance. The FAA considers an open prescription for diazepam disqualifying for medical certification and states that pilots using diazepam should not fly. Nordiazepam, oxazepam, and temazepam are active metabolites of diazepam. ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event) - [Takeoff: Dragged wing/rotor/float/other](https://openairdocs.org/ntsb-events/093) ## Aircraft - Registration: [N9728B](https://openairdocs.org/aircraft/N9728B), registered now, S/N 50026, built 1957 (OpenAirDocs) - Reported make and model: CESSNA 180A - Registry model: [Cessna 180A](https://openairdocs.org/model/cessna-180a) (registry code 2072604) (OpenAirDocs) - Registry engine: [Continental O-470 series](https://openairdocs.org/engine/continental-o-470-series) (registry code 17026, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 50026 - Year built: 1957 - Engines: CONT MOTOR O-470 SERIES 230 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Destination: LHD, Anchorage, AK - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 68; injuries: fatal; private; airplane ratings: single-engine sea; medical: basicmed; seat: left; restraint: 3-point; toxicology performed; flight hours: 679 total ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: 7,500 ft broken - Temperature: 54 °F, dew point 36 °F - Altimeter: 29.85 inHg - Observed at: AWS, 58 nm away - METAR: PAWS 252156Z AUTO VRB05KT 10SM BKN075 OVC090 12/02 A2985 RMK AO2 SLP111 T01220022 ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20220925016159A](https://openairdocs.org/incident/20220925016159A), Sep 25, 2022: Cessna 180A, Skwentna, AK, Substantial damage, 1 fatal. On September 25, 2022 at approximately 2309, a single engine Cessna 180A seaplane,[privacy data omitted] was destroyed when it impacted the water at [privacy… ## Docket (9 files) The files NTSB released with the investigation on February 28, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=105993. 21.5 MB in all. - Medical factual (item 1, PDF, 4 pages, 142 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15447605&FileExtension=pdf&FileName=ANC23LA080_Skwentna_AK_Medical_Factual_FINAL_050823-Rel.pdf - Witness statement (item 2, PDF, 1 page, 108 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15597916&FileExtension=pdf&FileName=MFR%20Rude-Rel.pdf - Wreckage examination (item 3, PDF, 10 pages, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16733985&FileExtension=pdf&FileName=Wreckge%20exam-Rel.pdf - Textron report (item 4, PDF, 10 pages, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15593432&FileExtension=pdf&FileName=Tech%20Report%2050026-Rel.pdf - Airworthiness records - float instillation (item 5, PDF, 2 pages, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15594418&FileExtension=pdf&FileName=N9728B-Airworthiness-float%20instillation_Redacted-Rel.pdf - Autopsy report memo for record (item 6, PDF, 1 page, 128 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15594321&FileExtension=pdf&FileName=Autopsy%20MFR-Rel.pdf - Statement of party representatives to NTSB investigation (item 7, PDF, 9 pages, 11.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15592653&FileExtension=pdf&FileName=ANC22LA080%20-%20Textron%20Party%20Form_Redacted-Rel.pdf - Toxicological report (item 8, PDF, 1 page, 872 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15593374&FileExtension=pdf&FileName=Toxicology%20Report_Redacted-Rel.pdf - Photos (item 9, PDF, 8 pages, 3.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15595752&FileExtension=pdf&FileName=Photos-Rel.pdf From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.