# NTSB ANC12CA025: Hughes 369, Trading Bay, AK, March 11, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: March 11, 2012, 15:30 local (23:30 UTC) - Place: Trading Bay, AK - Coordinates: 60.874443, -151.854721 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=60.8744&lon=-151.8547&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Dynamic rollover](https://openairdocs.org/ntsb-events/231) - Highest injury: No injuries - Injuries: 4 uninjured - Status: Completed, report June 28, 2012 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA Anchorage FSDO - NTSB case key (mKey): 83117 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC12CA025 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/83117/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=83117 - Page: https://openairdocs.org/ntsb/ANC12CA025 ## Probable cause The pilot's selection of an unsuitable landing site in flat-light conditions, which resulted in an inadvertent dynamic rollover. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: lateral/bank control](https://openairdocs.org/ntsb-findings/01062023): Aircraft › Aircraft oper/perf/capability · Capability exceeded; cases with it: [All aircraft, 390 cases](https://openairdocs.org/ntsb-findings/01062023/cases.md) - [Runway/land/takeoff/taxi surface: snow/slush/ice covered surface](https://openairdocs.org/ntsb-findings/03023015): Environmental issues › Physical environment · Awareness of condition; cases with it: [All aircraft, 219 cases](https://openairdocs.org/ntsb-findings/03023015/cases.md) - [Light condition: flat light](https://openairdocs.org/ntsb-findings/03036025): Environmental issues › Conditions/weather/phenomena · Effect on operation (probable cause); cases with it: [All aircraft, 42 cases](https://openairdocs.org/ntsb-findings/03036025/cases.md) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing: Dynamic rollover](https://openairdocs.org/ntsb-events/231) (defining event); cases with it: [All aircraft, 161 cases](https://openairdocs.org/ntsb-events/231/sequence.md) ## Analysis The pilot was landing at an off-airport site in flat-light conditions. After touchdown, the left skid sank into the snow, and the helicopter began rolling to the left. The pilot attempted to correct the roll with right cyclic input but overcorrected, and the helicopter entered a dynamic roll to the right. The helicopter came to rest on its right side, sustaining substantial damage to the tailboom and the main rotor drive system. The pilot stated that there were no preaccident mechanical anomalies with the helicopter. ## Factual narrative The pilot was landing at an off-airport site in flat-light conditions. After touchdown, the left skid sank into the snow, and the helicopter began rolling to the left. The pilot attempted to correct the roll with right cyclic input, but over corrected, and the helicopter entered a dynamic roll to the right, receiving substantial damage to the tail boom, and main rotor drive system. The pilot stated there were no preaccident mechanical anomalies with the helicopter. ## Aircraft - Registration: C-GVEB (not matched to a registry record) - Reported make and model: HUGHES 369 (D) - Category: Helicopter - Serial number: 611006D - Airframe hours: 13207 - Engines: ALLISON 250 turbo shaft - Damage: Substantial damage - Flight: Part 135 - Operator: Prism Helicopters Inc - Registered owner: Prism Helicopters Ltd. - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, February 13, 2012, 53 hours before - Departed: Trading Bay, AK - Destination: Trading Bay, AK - Flight plan: Company VFR - Airport: runway 36, snow ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 65; injuries: none; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: helicopter, airplane; medical: class 2, with waivers/limitations; last flight review March 4, 2012; seat: left; flight hours: 22,560 total, 5,450 in this make and model, 17 in the last 90 days, 17 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 5 statute miles - Temperature: 18 °F - Altimeter: 29.94 inHg ## Docket (1 files) The files NTSB released with the investigation on May 22, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=83117. 3.0 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40367713&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.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.