ERA21LA262 · McDonnell Douglas Helicopter 369E
Haverfield International McDonnell Douglas Helicopter 369E · Accident: low altitude operation/event while maneuvering
From Sullivan County International Airport (MSV) to an unrecorded destination
Event
- NTSB case
- ERA21LA262
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
McDonnell Douglas Helicopter 369E
- Aircraft type
- McDonnell Douglas 369
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N371EE
- Operator
- Haverfield International
- Onboard fatalities
- Unknown
- Route
- From Sullivan County International Airport (MSV), Monticello, NYTo not recorded
- Aircraft age
- About 32 years (built 1989)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 133: Rotorcraft Ext. Load
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Maneuvering · hover
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Low altitude operation/event
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Pole
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft oper/perf/capability
- Environmental issues › Physical environment
- Personnel issues › Psychological
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The pilot positioned the helicopter near one of the power transmission tower structures as the lineman, seated on a platform that was attached externally on the skids, began the maintenance. The pilot and the lineman both reported that they then heard a bang, and the helicopter began to shake violently. The pilot maneuvered the helicopter away from the tower and descended through the tree branches. The helicopter came to rest upright in a heavily wooded area. A microscopic postaccident examination of one main rotor blade tip revealed witness marks consistent with metal impact, and a support bracket for the tower catwalk displayed impact damage. A postaccident examination of the airframe and engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation of the helicopter. A postaccident examination of the tower revealed that, unlike the majority of the towers being maintained, it was equipped with a catwalk which had a lifeline support bracket protruding from the top of it for the tower catwalk. Given this information, it is likely that the pilot did not note this hazard and that main rotor blade tip impacted the tower structure and resulted in the subsequent loss of control.
Probable cause
The pilot's failure to maintain adequate clearance from the power transmission tower structure during powerline maintenance work, which resulted in the helicopter's main rotor striking the lifeline support bracket for the tower catwalk and the subsequent loss of control and collision with terrain.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA21LA262
- Event ID
- 20210621103303
- Case number
- ERA21LA262
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates, cause areas. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: ad7b6d784c18ca1cef36bc7cd26f7d97d8600343eb1a4b5f7063b31e5c865c5b; retrieved 2026-09-16T14:11:35.565Z.