# NTSB ANC20LA099: Cessna 170B, N4380B, Big Lake, AK, September 23, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: September 22, 2020, 19:00 local (Sep 23, 2020, 03:00 UTC) - Place: Big Lake, AK - Coordinates: 61.587423, -150.3984 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=61.5874&lon=-150.3984&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Fuel related](https://openairdocs.org/ntsb-events/190) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Alaska Regional Office - Parties: FAA - SAIBs cited in the narratives: [SAIB CE-09-35](https://openairdocs.org/saib/CE-09-35) (OpenAirDocs) - NTSB case key (mKey): 102060 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC20LA099 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102060/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=102060 - Page: https://openairdocs.org/ntsb/ANC20LA099 ## Probable cause The pilot’s failure to utilize carburetor heat while flying in conditions conducive to carburetor icing, which resulted in a total loss of engine power. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Action: lack of action](https://openairdocs.org/ntsb-findings/02041030): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Cessna 170B, 1 case](https://openairdocs.org/ntsb-findings/02041030/cases.md?model=2072306), [All aircraft, 792 cases](https://openairdocs.org/ntsb-findings/02041030/cases.md) - [Ice/rain protection system: intake anti-ice, deice](https://openairdocs.org/ntsb-findings/01023020): Aircraft › Aircraft systems · Not used/operated (probable cause); cases with it: [Cessna 170B, 1 case](https://openairdocs.org/ntsb-findings/01023020/cases.md?model=2072306), [All aircraft, 108 cases](https://openairdocs.org/ntsb-findings/01023020/cases.md) - [Temp/humidity/pressure: conducive to carburetor icing](https://openairdocs.org/ntsb-findings/03031030): Environmental issues › Conditions/weather/phenomena · Contributed to outcome (probable cause); cases with it: [Cessna 170B, 2 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md?model=2072306), [All aircraft, 435 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing: Fuel related](https://openairdocs.org/ntsb-events/190) (defining event); cases with it: [Cessna 170B, 1 case](https://openairdocs.org/ntsb-events/190/sequence.md?model=2072306), [All aircraft, 361 cases](https://openairdocs.org/ntsb-events/190/sequence.md) - [Landing: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Cessna 170B, 5 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=2072306), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Landing: Landing area undershoot](https://openairdocs.org/ntsb-events/370); cases with it: [Cessna 170B, 2 cases](https://openairdocs.org/ntsb-events/370/sequence.md?model=2072306), [All aircraft, 201 cases](https://openairdocs.org/ntsb-events/370/sequence.md) - [Landing-flare/touchdown: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Cessna 170B, 29 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=2072306), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis During a landing to a remote off-airport gravel bar located along a river, while at about 20 ft above ground level, the airplane’s engine lost power. The engine then surged briefly before a total loss of engine power occurred. Subsequently, the airplane landed short of the gravel bar in the river and the airplane nosed over. The airplane sustained substantial damage to the left wing and empennage. A postaccident examination revealed no mechanical failures or malfunctions. A postaccident engine run was successfully performed. A non-aviation fuel tank was installed on the top of the fuselage to provide a fuel source. Air was applied to the fuel lines to provide pressure to ensure proper fuel flow, no contaminates were noted in the fuel lines. The temperature and dew point were entered into a carburetor icing probability chart, which coincided with the “serious icing in glide power” category. ## Factual narrative On September 22, 2020, about 1900 Alaska daylight time, a Cessna 170B, N4380B, was substantially damaged when it was involved in an accident near Big Lake, Alaska. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 flight. According to the pilot, he was landing on a remote off-airport gravel bar located along a river. During short final, at about 20 ft above ground level, the airplane’s engine sputtered followed by a partial loss of power. The engine then surged briefly followed by a total loss of engine power as the propeller continued to windmill. Subsequently, the airplane touched down in the river short of the gravel bar and nosed over, coming to rest inverted in the river. The airplane sustained substantial damage to the left wing and empennage. The pilot reported that he had flown for about 1.5 hours prior to the accident and had about 1.7 hours of fuel remaining in the airplane’s fuel tanks at the time of the accident. He reported that he had been applying carburetor heat during his previous landings at the gravel bar and the fuel tank selector was set to BOTH during the approach. A Federal Aviation Administration (FAA) aviation safety inspector examined the airplane after recovery and did not observe any abnormalities. He stated that he drained the fuel from the gascolator and the fuel looked normal with no contamination present. A postaccident engine run was successfully performed. A non-aviation fuel tank was installed on the top of the fuselage to provide a fuel source. Air was applied to the fuel lines to provide pressure to ensure proper fuel flow, no contaminates were noted in the fuel lines. The weather observation station located about 25 nautical miles away from the accident site reported that, about the time of the accident, the temperature was 55.4° F and dew point 37.4° F. According to the carburetor icing-probability chart located in FAA Special Airworthiness Information Bulletin CE-09-35, the accident flight would have been operating in “serious icing in glide power”. ## Aircraft - Registration: [N4380B](https://openairdocs.org/aircraft/N4380B), registered now, S/N 26724 (OpenAirDocs) - Reported make and model: CESSNA 170B - Registry model: [Cessna 170B](https://openairdocs.org/model/cessna-170b) (registry code 2072306) (OpenAirDocs) - Registry engine: [Continental 0-300 series](https://openairdocs.org/engine/continental-0-300-series) (registry code 17022, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 26724 - Year built: 1955 - Airframe hours: 3295 - Engines: Franklin PZL 6A-350-C2 220 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Daniel Elias - Airworthiness certificate: Standard, Normal - Last inspection: Annual, May 31, 2020 - Departed: MRL, Anchorage, AK - Destination: Same as departure - Flight plan: VFR - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 37; injuries: none; commercial, airline transport; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; seat: left; restraint: 3-point; flight hours: 8,839 total, 297 in this make and model, 5,968 as pilot in command, 173 in the last 90 days, 68 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 40° at 9 knots, gusting 14 - Visibility: 10 statute miles - Lowest ceiling: 8,500 ft overcast - Temperature: 55 °F, dew point 37 °F - Altimeter: 29.31 inHg - Observed at: PAWS, 25 nm away ## 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 20200922012459A](https://openairdocs.org/incident/20200922012459A), Sep 22, 2020: Cessna 170B, Big Lake, AK, Substantial damage. Pilot was landing on a gravel bar on the big susitna river. While on short final at 20 ft. elevation the aircraft loss power. The aircraft touched down short… ## Docket (6 files) The files NTSB released with the investigation on March 21, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=102060. 4.0 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 580 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11463407&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Pilot roc (item 2, PDF, 1 page, 78 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11489211&FileExtension=pdf&FileName=Pilot%20ROC-Rel.pdf - Salvage company roc (item 3, PDF, 1 page, 79 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11487490&FileExtension=pdf&FileName=Salvage%20Company%20ROC-Rel.pdf - Examination notes (item 4, PDF, 3 pages, 2.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11462843&FileExtension=pdf&FileName=Examination%20Notes_Redacted-Rel.pdf - Carburetor icing probability graph (item 5, PDF, 1 page, 155 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11501769&FileExtension=pdf&FileName=Carburetor%20Icing%20Probability%20Graph-Rel.pdf - Accident pictures (item 6, PDF, 4 pages, 774 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11465605&FileExtension=pdf&FileName=Accident%20Pictures-Rel.pdf From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; 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.