NTSB CAROL · Event
Event LAX04CA233
Aircraft involved
Probable cause & findings
the student's improper use of the cyclic control, the flight instructor's inadequate supervision, and his delayed remedial action. A factor in the accident was the CFI's diverted attention.
Factual narrative
On June 5, 2004, about 1600 Pacific daylight time, a Schweizer 269C-1, N9421K, collided with terrain and rolled over near Brentwood, California. Helicopter Adventures, Inc., was operating the helicopter under the provisions of 14 CFR Part 91. The certified flight instructor (CFI) and the student pilot were not injured; the helicopter sustained substantial damage. The local instructional flight departed Buchanan Field Airport, Concord, California, about 1500. Visual meteorological conditions prevailed, and a company visual flight rules flight plan had been filed. The wreckage was at 37 degrees 53 minutes north latitude and 121 degrees 45 minutes west longitude. In a written statement, the operator of the helicopter stated that the CFI had planned to take the student pilot to the Silva Ranch practice area, about 15 miles east of Concord. During the en route portion of the flight, the student practiced maneuvering the helicopter in straight and level flight. Upon arriving at the practice area (a large flat valley), the CFI instructed the student on hover techniques by demonstrating the use of control inputs. The student practiced maneuvering the helicopter via the use of a sole control input, starting with pedals, then collective, followed by cyclic. While the student was manipulating the cyclic, the CFI noted that the friction setting on the collective had been engaged, and he attempted to disengage it. As the CFI was focusing his attention on the friction setting for the collective, the student made a large forward cyclic input. The CFI input aft cyclic and increased the collective in an effort to counteract the student's abrupt maneuver and maintain ground separation. The helicopter impacted the ground and rolled over. In a written statement, the CFI reported that, while maneuvering about 3 to 4 feet above ground level, he noticed that the collective was difficult to adjust. He glanced down at the collective and realized that the collective friction had been activated. (According to the Schweitzer Pilot's Operating Handbook, the friction control is activated by adjustment of a lever.) While the CFI attempted to adjust the friction setting, the student made a large forward cyclic input. The helicopter responded in an extreme nose down position and began to move forward. The helicopter impacted terrain and rolled over the nose, coming to rest on the right side. The CFI reported no preimpact mechanical malfunctions or failures with the helicopter. The helicopter collided with terrain and rolled over while hovering above flat terrain. The student pilot was practicing hover techniques by utilizing the controls individually. While the student was manipulating the cyclic, the certified flight instructor (CFI) noticed that the friction setting on the collective had been engaged. As the CFI was focusing on the friction setting for the collective, the student made a large forward cyclic input. The helicopter responded in an extreme nose down position and the CFI attempted to counteract the student's abrupt maneuver. The helicopter impacted terrain and rolled over the nose, coming to rest on the right side. The CFI reported no preimpact mechanical malfunctions or failures with the helicopter. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12
Verbatim from NTSB's published report. Source file
NTSB_2004_LAX04CA233.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
What the literature says.
Academic papers and agency reports matching this event's aircraft type or causal vocabulary (icing). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.
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- arXiv 2025 · arXiv preprint
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- Embry-Riddle Scholarly Commons 2025 · Journal article (JAAER)
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NASA Icing Update – March 2025
This NASA Icing Update was prepared for presentation to the SAE International AC-9C Inflight Icing Technology Committee. This update includes the following topics: planned Rotational Icing Scaling tes…
- arXiv 2024 · arXiv preprint
An energy-stable phase-field model for droplet icing simulations
A phase-field model for three-phase flows is established by combining the Navier-Stokes (NS) and the energy equations, with the Allen-Cahn (AC) and Cahn-Hilliard (CH) equations and is demonstrated ana…
- NASA NTRS 2024 · Presentation
NASA Icing Update – Oct 2024
This presentation provides a status update on select NASA icing research activities for the SAE AC-9C Icing Technical Committee Meeting on Oct 21, 2024.
Browse the full corpus — academia portal ↗