# NTSB ANC21LA083: Mcdonnell Douglas Helicopter 369E, N125KW, Delta Junction, AK, September 7, 2021 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 4 · Limited · Final report - Date: September 6, 2021, 17:40 local (Sep 7, 2021, 01:40 UTC) - Place: Delta Junction, AK · Healy Lake - Coordinates: 63.999752, -144.73459 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=63.9998&lon=-144.7346&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Roll over](https://openairdocs.org/ntsb-events/097) - Highest injury: Minor injuries - Injuries: 1 minor, 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Alaska Regional Office - Parties: FAA - NTSB case key (mKey): 103817 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC21LA083 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103817/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103817 - Page: https://openairdocs.org/ntsb/ANC21LA083 ## Probable cause The pilot’s inability to maintain lateral control during the takeoff, which resulted in dynamic rollover. Contributing to the accident was the pilot’s decision to utilize an unsuitable landing area for flight operations. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters](https://openairdocs.org/ntsb-findings/01062000): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Mcdonnell Douglas Helicopter 369E, 2 cases](https://openairdocs.org/ntsb-findings/01062000/cases.md?model=3027369), [All aircraft, 1,269 cases](https://openairdocs.org/ntsb-findings/01062000/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Mcdonnell Douglas Helicopter 369E, 6 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=3027369), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Mcdonnell Douglas Helicopter 369E, 1 case](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=3027369), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Runway/land/takeoff/taxi surface](https://openairdocs.org/ntsb-findings/03023000): Environmental issues › Physical environment · Ability to respond/compensate; cases with it: [Mcdonnell Douglas Helicopter 369E, 1 case](https://openairdocs.org/ntsb-findings/03023000/cases.md?model=3027369), [All aircraft, 253 cases](https://openairdocs.org/ntsb-findings/03023000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Roll over](https://openairdocs.org/ntsb-events/097) (defining event); cases with it: [Mcdonnell Douglas Helicopter 369E, 1 case](https://openairdocs.org/ntsb-events/097/sequence.md?model=3027369), [All aircraft, 261 cases](https://openairdocs.org/ntsb-events/097/sequence.md) - [Takeoff: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490); cases with it: [Mcdonnell Douglas Helicopter 369E, 3 cases](https://openairdocs.org/ntsb-events/490/sequence.md?model=3027369), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md) ## Analysis The pilot was transporting personnel from a remote helipad that was constructed of a plastic, floating dock. She was unaware that the helicopter’s right skid had slid under a portion of the plastic dock. As she raised the collective to depart, she felt the helicopter roll to the right, and she attempted to correct the lateral rolling motion by lowering the collective. The helicopter continued to roll and came to rest on its right side. Subsequently, the helicopter sustained substantial damage to the main rotor system. The pilot reported no preimpact mechanical failures or malfunctions with the helicopter that would have precluded normal operation. ## Aircraft - Registration: [N125KW](https://openairdocs.org/aircraft/N125KW), registered now, S/N 0336E, built 1989 (OpenAirDocs) - Reported make and model: MCDONNELL DOUGLAS HELICOPTER 369E - Registry model: [Mcdonnell Douglas Helicopter 369E](https://openairdocs.org/model/mcdonnell-douglas-helicopter-369e) (registry code 3027369) (OpenAirDocs) - Registry engine: [Rolls-Royce 250-C20B](https://openairdocs.org/engine/rolls-royce-250-c20b) (registry code 54385, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 0336E - Year built: 1989 - Engines: ROLLS-ROYCE 250-C20B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Business, Part 135 - Registered owner: Aurora Aviation Services Inc - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, September 5, 2021 - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 24; injuries: none; flight instructor, airline transport; instrument ratings: helicopter; medical: class 1, without waivers/limitations; last flight review July 25, 2021; seat: left; restraint: 4-point; flight hours: 1,921 total, 25 in this make and model, 1,852 as pilot in command, 67 in the last 90 days, 16 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 90° at 5 knots - Visibility: 10 statute miles - Temperature: 48 °F, dew point 37 °F - Altimeter: 29.96 inHg - Observed at: PABI, 26 nm away - METAR: PABI 070153Z 09005KT 10SM SCT022 SCT027 09/03 A2996 RMK AO2 SLP157 T00940028 ## 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 20210906014469A](https://openairdocs.org/incident/20210906014469A), Sep 6, 2021: Mcdonnell Douglas Helicopter 369E, Delta Junction, AK, Substantial damage. The landing pad was made of heavy plastic dock panels(approx. 1000# each) made into the shape of an h. As the pilot approached the landing pad, she elected to… ## Docket (2 files) The files NTSB released with the investigation on March 21, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103817. 1.8 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12740747&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Accident pictures (item 2, PDF, 3 pages, 239 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12741307&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.