# NTSB ANC11TA110: Bell 206 B3, N204PA, Seward, AK, September 23, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Final report - Date: September 23, 2011, 13:30 local (21:30 UTC) - Place: Seward, AK - Coordinates: 60.070556, -149.953338 - Nearby events: https://openairdocs.org/map.md?lat=60.0706&lon=-149.9533&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of visual reference](https://openairdocs.org/ntsb-events/402) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report April 10, 2013 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA FSDO-03 - NTSB case key (mKey): 81905 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC11TA110 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81905/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81905 - Page: https://openairdocs.org/ntsb/ANC11TA110 ## Probable cause The pilot's failure to maintain clearance from snow-covered terrain during hover in deteriorating weather and flat light conditions, which resulted in a tail rotor strike. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Bell 206-L4, 4 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=1182110), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Ceiling/visibility/precip: whiteout](https://openairdocs.org/ntsb-findings/03035060): Environmental issues › Conditions/weather/phenomena · Contributed to outcome; cases with it: [Bell 206-L4, 1 case](https://openairdocs.org/ntsb-findings/03035060/cases.md?model=1182110), [All aircraft, 13 cases](https://openairdocs.org/ntsb-findings/03035060/cases.md) - [Terrain: snowy/icy terrain](https://openairdocs.org/ntsb-findings/03021030): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Bell 206-L4, 1 case](https://openairdocs.org/ntsb-findings/03021030/cases.md?model=1182110), [All aircraft, 77 cases](https://openairdocs.org/ntsb-findings/03021030/cases.md) - [Tail rotor: tail rotor blade](https://openairdocs.org/ntsb-findings/01046410): Aircraft › Aircraft propeller/rotor · Damaged/degraded; cases with it: [Bell 206-L4, 1 case](https://openairdocs.org/ntsb-findings/01046410/cases.md?model=1182110), [All aircraft, 31 cases](https://openairdocs.org/ntsb-findings/01046410/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: [Bell 206-L4, 4 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=1182110), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Bell 206-L4, 8 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=1182110), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Loss of visual reference](https://openairdocs.org/ntsb-events/402) (defining event); cases with it: [Bell 206-L4, 1 case](https://openairdocs.org/ntsb-events/402/sequence.md?model=1182110), [All aircraft, 242 cases](https://openairdocs.org/ntsb-events/402/sequence.md) - [Maneuvering-low-alt flying: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Bell 206-L4, 8 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=1182110), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The commercial helicopter pilot, with two passengers aboard, was supporting a snow survey crew atop an expansive, smooth, featureless, and snow-covered glacial ice field. This operation required brief stops at various predetermined sites along a prearranged route. When the pilot departed from one site en route to the next predetermined site, deteriorating weather conditions coupled with flat light conditions hampered his ability to see the topographical features of the ice field below. As the pilot slowed the helicopter to make a precautionary landing, the helicopter “touched down early.” After the initial touchdown, the pilot hover-taxied the helicopter to an area about 20 or 30 yards beyond the initial touchdown point, then he landed the helicopter in the deep snow. After landing, the helicopter tipped backwards as the aft portion of the skids settled into the deep snow, and the tail rotor blades subsequently struck the snow. The operator reported no preaccident mechanical problems with the helicopter. Before the helicopter could be ferried from the site, a maintenance technician inspected the helicopter for damage. Finding no apparent damage, the helicopter was started, ground run, and then hovered. While hovering, a tail rotor driveshaft coupling separated, and the pilot did a hovering autorotation back to the snow-covered ice field. As a result of the tail rotor driveshaft coupling separation, the helicopter sustained substantial damage to the tail rotor drive shaft assembly. The damage to the tail rotor drive shaft occurred as the helicopter was being ferried from the site, not during the original event. Most likely the drive shaft was degraded during the first landing, but it did not separate until the ferry flight. ## Factual narrative On September 23, 2011, about 1330 Alaska daylight time, a high skid-equipped Bell 206B3 helicopter, N204PA, sustained substantial damage during a tail rotor strike while maneuvering to land on the Harding Ice Field, about 10 miles west of Seward, Alaska. The helicopter was owned and operated by Pathfinder Aviation, Homer, Alaska, as a visual flight rules (VFR) public use passenger flight, in conjunction with the National Park Service (NPS), under the provisions of 14 Code of Federal Regulations Part 135, when the accident occurred. The commercial pilot and the two passengers were not injured. Visual meteorological conditions prevailed at the time of departure, and company flight following procedures were in effect. The flight originated about 1320 from a remote site on the Harding Ice Field. According to the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by the operator, dated October 25, along with subsequent conversations with Pathfinder Aviation’s director of operations, the purpose of flight was to transport two NPS employees to a remote snow-covered site on the Harding Ice Field to collect snow samples. The mission required brief stops at various predetermined sites along a prearranged route. The director of operations noted that when the pilot departed from the previous site, en route to the next predetermined site, weather conditions were “good VFR.” As the flight progressed towards the upper elevations of the ice field, the pilot encountered overcast layers and flat light conditions. According to the director of operations, as the pilot slowed the helicopter to make a precautionary landing, and while on approach, “the aircraft touched down early.” After the initial touchdown, the pilot hovered-taxied the helicopter to an area about 20 or 30 yards beyond the initial touchdown point, then he landed the helicopter in the deep snow. After landing, the helicopter tipped backwards as the aft portion of the skids settled into the deep snow, and the tail rotor blades subsequently struck the snow. There were no preaccident mechanical problems reported with the helicopter. In a written statement to the NTSB dated September 24, a passenger aboard the accident helicopter reported that while traveling from one landing site on the Harding Ice Field to another, visibility deteriorated rapidly, making it very difficult to discern any topographic features of the snow-covered ice field. He said that as the pilot began slowing the helicopter, he estimated the helicopter’s height above the ice to be 100 feet, and then the helicopter unexpectedly touched down. After the initial touchdown, the helicopter continued to hover momentarily, then the pilot immediately landed the helicopter, and it tipped backwards. Photos of the accident site were provided to the NTSB as part of the passenger’s written statement. The topographical features surrounding the accident site consisted of expansive, smooth, featureless, and snow-covered slopingterrain. According to Pathfinder Aviation’s director of operations, a company maintenance technician was flown by helicopter to the site to inspect the helicopter for damage before it could be ferried back to Seward. Finding no apparent damage, the helicopter was started, ground run, and then hovered. While hovering, a tail rotor driveshaft coupling separated, and the pilot did a hovering autorotation back to the snow-covered ice field. As a result, the helicopter sustained substantial damage to the tail rotor drive shaft assembly. In the recommendations section of the NTSB 6120.1 form submitted by the operator, the director of operations noted that future pilot training would include formal flat light and whiteout training, as well as added training on judgment and decision making regarding weather. ## Aircraft - Registration: [N204PA](https://openairdocs.org/deregistered/N204PA-2022-03-18), registration cancelled 2022-03-18, S/N 52276, built 2003 (OpenAirDocs) - Reported make and model: BELL 206 B3 - Registry model: [Bell 206-L4](https://openairdocs.org/model/bell-206-l4) (registry code 1182110) (OpenAirDocs) - Registry engine: [Allison 250-C30 series](https://openairdocs.org/engine/allison-250-c30-series) (registry code 03015, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 1742 - Airframe hours: 13347 - Engines: Allison 250 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Public aircraft - federal, Public use - Operator: Pathfinder Aviation, doing business as Pathfinder Aviation - Registered owner: Pathfinder Leasing Inc - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, August 13, 2011 - Departed: PAWD, Seward, AK - Destination: Seward, AK - Flight plan: VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 30; injuries: none; commercial; medical: class 2, without waivers/limitations; last flight review July 18, 2011; seat: right; flight hours: 1,860 total, 392 in this make and model, 1,835 as pilot in command, 160 in the last 90 days, 39 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: 500 ft overcast - Temperature: 43 °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 20110923023089A](https://openairdocs.org/incident/20110923023089A), Sep 23, 2011: Bell 206B, Seward, AK, Substantial damage. Pilot stated that he was trying to reach his next landing site on the glacier and at first he could see under the overcast. As he progressed out over the… ## Docket (3 files) The files NTSB released with the investigation on February 5, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81905. 3.3 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40385031&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Witness Statement (item 2, .PDF, 694 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40385033&FileExtension=.PDF&FileName=Witness%20Statement-Master.PDF - IHST Helicopter Supplemental Checklist (item 3, .PDF, 74 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40385246&FileExtension=.PDF&FileName=IHST%20Helicopter%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.