# NTSB ANC10CA040: Robinson Helicopter R44, N81191, Seward, AK, May 15, 2010 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: May 15, 2010, 10:40 local (18:40 UTC) - Place: Seward, AK - Coordinates: 60.233333, -149.383331 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=60.2333&lon=-149.3833&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: 2 uninjured - Status: Completed, report August 12, 2010 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: Federal Aviation Administration (Airworthiness) - NTSB case key (mKey): 76051 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC10CA040 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/76051/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=76051 - Page: https://openairdocs.org/ntsb/ANC10CA040 ## Probable cause The pilot's failure to maintain clearance from snow-covered terrain while hovering 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: [Robinson Helicopter R44, 1 case](https://openairdocs.org/ntsb-findings/03036025/cases.md?model=7640120), [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: [Robinson Helicopter R44, 6 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md?model=7640120), [All aircraft, 559 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md) - [Performance/control parameters: altitude](https://openairdocs.org/ntsb-findings/01062012): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Robinson Helicopter R44, 22 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=7640120), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/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: [Robinson Helicopter R44, 8 cases](https://openairdocs.org/ntsb-events/231/sequence.md?model=7640120), [All aircraft, 161 cases](https://openairdocs.org/ntsb-events/231/sequence.md) ## Analysis The commercial helicopter pilot reported that he was on a Title 14, Code of Federal Regulations Part 91, business flight transporting a passenger and seven dogs to a remote camp. As he approached the camp, which was at 3,800 feet mean seal level on a snow-covered glacier, flat light conditions made it difficult to discern topographical features on the glacier, so he elected to land at an alternate landing site at 3,200 feet msl to wait for conditions to improve. During the approach to the alternate site, just before touchdown, the pilot said that the low rotor annunciator horn sounded and that he lowered the collective to regain rotor rpm. The pilot was unable to initiate a go-around so he brought the helicopter to a hover, but due to the prevailing flat light he was unable to discern his height above the site and he unintentionally allowed the helicopter's left skid to touchdown on the uneven, snow-covered terrain. He said that there was an "instantaneous dynamic rollover" as the helicopter rolled to the left, the main rotor blades struck the snow, and the helicopter came to rest inverted. The helicopter sustained substantial damage to the fuselage, tail boom and main rotor drive system. In his written statement to the NTSB, the pilot reported that there were no preaccident mechanical problems with the helicopter, and in the recommendations section of the NTSB 6120.1 form he wrote, in part: "Always keep an 'out' or rejected approach path if conditions are unfavorable on short final." He also noted that he underestimated the difficulties associated with flat light over snow-covered terrain. ## Factual narrative The commercial helicopter pilot reported that he was on a Title 14, CFR Part 91 business flight transporting one passenger and seven dogs to a remote camp. He said as he approached the camp, which was at 3,800 feet msl on a snow-covered glacier, flat light conditions made it difficult to discern topographical features on the glacier, so he elected to land at an alternate landing site at 3,200 feet msl to wait for conditions to improve. During the approach to the alternate site, just before touchdown, the pilot said the low rotor annunciator horn sounded, and he lowered the collective to regain rotor rpm. The pilot said he was unable to initiate a go-around, so he brought the helicopter to a hover, but due to the prevailing flat light he was unable to discern his height above the site, and he unintentionally allowed the helicopter's left skid to touchdown on the uneven, snow-covered terrain. He said that there was an "instantaneous dynamic rollover" as the helicopter rolled to the left, the main rotor blades struck the snow, and the helicopter came to rest inverted. The helicopter sustained substantial damage to the fuselage, tail boom and main rotor drive system. In his written statement to the NTSB, the pilot reported that there were no preaccident mechanical problems with the helicopter, and in the recommendations section of the NTSB 6120.1 form he wrote, in part: "Always keep an 'out' or rejected approach path if conditions are unfavorable on short final." He also noted that he underestimated the difficulties associated with flat light over snow-covered terrain. ## Aircraft - Registration: [N81191](https://openairdocs.org/aircraft/N81191), registered now, S/N 0855 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER R44 - Registry model: [Robinson Helicopter R44](https://openairdocs.org/model/robinson-helicopter-r44) (registry code 7640120) (OpenAirDocs) - Category: Helicopter - Serial number: 0855 - Airframe hours: 2468 - Engines: Lycoming O-540-F1B5 260 horsepower reciprocating - Damage: Substantial damage - Flight: Business, Part 91 - Operator: Polux Aviation - Registered owner: Castor Aviation LTD - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, April 8, 2010, 22 hours before - Departed: Seward, AK - Destination: Seward, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 42; injuries: none; commercial, flight instructor; medical: class 2, without waivers/limitations; last flight review April 17, 2010; seat: right; flight hours: 967 total, 70 in this make and model, 835 as pilot in command, 45 in the last 90 days, 20 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 120° at 15 knots - Visibility: 10 statute miles - Lowest ceiling: 4,000 ft broken - Temperature: 30 °F - Altimeter: 29.79 inHg ## 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 20100515033829A](https://openairdocs.org/incident/20100515033829A), May 15, 2010: Robinson He R44, Seward, AK, Substantial damage. Lost control landing on snow covered glacier, aircraft rolled over on back. Flat light/white out. ## Docket (2 files) The files NTSB released with the investigation on July 7, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=76051. 828 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 696 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40332580&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - HAI Helicopter Accident Checklist (item 2, .PDF, 133 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40332581&FileExtension=.PDF&FileName=HAI%20Helicopter%20Accident%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.