# NTSB ANC13CA041: Bell Helicopter Textron 206L-1, N1171, Anaktuvuk Pass, AK, May 1, 2013 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: April 30, 2013, 16:30 local (May 1, 2013, 00:30 UTC) - Place: Anaktuvuk Pass, AK - Coordinates: 68.150962, -151.710296 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=68.1510&lon=-151.7103&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-flare/touchdown: Dynamic rollover](https://openairdocs.org/ntsb-events/231) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report July 29, 2013 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: Federal Aviation Administration - NTSB case key (mKey): 86822 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC13CA041 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/86822/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=86822 - Page: https://openairdocs.org/ntsb/ANC13CA041 ## Probable cause The pilot's failure to maintain lateral control while hovering over an area of snow-covered terrain, in flat light conditions, which resulted in a dynamic rollover. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Light condition: flat light](https://openairdocs.org/ntsb-findings/03036025): Environmental issues › Conditions/weather/phenomena · Contributed to outcome; cases with it: [Bell Helicopter Textron 206L-1, 1 case](https://openairdocs.org/ntsb-findings/03036025/cases.md?model=1182107), [All aircraft, 42 cases](https://openairdocs.org/ntsb-findings/03036025/cases.md) - [Info processing/decision: identification/recognition](https://openairdocs.org/ntsb-findings/02041510): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Bell Helicopter Textron 206L-1, 4 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md?model=1182107), [All aircraft, 559 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md) - [Performance/control parameters: lateral/bank control](https://openairdocs.org/ntsb-findings/01062023): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Bell Helicopter Textron 206L-1, 1 case](https://openairdocs.org/ntsb-findings/01062023/cases.md?model=1182107), [All aircraft, 390 cases](https://openairdocs.org/ntsb-findings/01062023/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-flare/touchdown: Dynamic rollover](https://openairdocs.org/ntsb-events/231) (defining event); cases with it: [Bell Helicopter Textron 206L-1, 3 cases](https://openairdocs.org/ntsb-events/231/sequence.md?model=1182107), [All aircraft, 161 cases](https://openairdocs.org/ntsb-events/231/sequence.md) ## Analysis The commercial helicopter pilot reported that while flying over an area of flat and featureless, snow-covered terrain, deteriorating weather conditions with low ceilings, light snow, and flat light conditions reduced his visibility, so he elected to make a precautionary landing to wait for improved visibility. He said that while attempting to land, blowing snow from the main rotor downwash reduced his ability to discern topographical features on the snow-covered terrain. During touchdown, the helicopter drifted to the left, the left skid struck the snow-covered terrain, and the helicopter rolled onto its left side. The helicopter sustained substantial damage to the rotor system, tail boom, and fuselage. The operator reported that there were no preaccident mechanical malfunctions or anomalies that would have precluded normal operation. ## Factual narrative The commercial helicopter pilot reported that while flying over an area of flat and featureless, snow-covered terrain, deteriorating weather conditions with low ceilings, light snow, and flat light conditions reduced his visibility, so he elected to make a precautionary landing to wait for improving visibility. He said that while attempting to land, blowing snow from the main rotor downwash reduced his ability to discern topographical features on the snow-covered terrain. During touchdown, the helicopter drifted to the left, the left skid struck the snow-covered terrain, and the helicopter rolled onto its left side. The helicopter sustained substantial damage to the rotor system, tail boom, and fuselage. The operator reported that there were no preaccident mechanical malfunctions or anomalies that would have precluded normal operation. ## Aircraft - Registration: [N1171](https://openairdocs.org/aircraft/N1171), registered now, S/N 45234, built 1979 (OpenAirDocs) - Reported make and model: BELL HELICOPTER TEXTRON 206L-1 - Registry model: [Bell Helicopter Textron 206L-1](https://openairdocs.org/model/bell-helicopter-textron-206l-1) (registry code 1182107) (OpenAirDocs) - Registry engine: [Allison 250-C28B](https://openairdocs.org/engine/allison-250-c28b) (registry code 03114, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 45234 - Airframe hours: 29902 - Engines: Rolls Royce C30P 650 horsepower turbo shaft - Damage: Substantial damage - Flight: Part 135 - Operator: Pathfinder Aviation - Registered owner: Gm Leasing Co LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, February 1, 2013 - Departed: Kuparik River, AK - Destination: PAUM, Umiat, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 51; injuries: none; commercial; medical: class 2, without waivers/limitations; last flight review March 26, 2013; seat: right; flight hours: 7,350 total, 4,670 in this make and model, 7,300 as pilot in command, 40 in the last 90 days, 40 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Instrument (IMC), Day - Wind: 210° at 10 knots - Visibility: 1 statute miles - Temperature: 19 °F ## 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 20130430006769A](https://openairdocs.org/incident/20130430006769A), Apr 30, 2013: Bell Helicopter Textron 206L-1, Umiat, AK, Substantial damage. Pilot entered low visability snow squall. Decided to set down and wait out weather. Upon landing, lost sight of ground due to blowing snow from rotor, lt skid… ## Docket (2 files) The files NTSB released with the investigation on June 3, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=86822. 702 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 589 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40392614&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Helicopter Supplemental Checklist (item 2, .PDF, 114 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40392656&FileExtension=.PDF&FileName=Helicopter%20Supplemental%20Checklist-Master.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.