Casualties unknown

Helicopter Rolls Over During Hover Training with Student and Instructor (N9421K)

Brentwood, CA, US

On June 5, 2004, a Schweizer 269C-1 (registration N9421K) operated by Helicopter Adventures Inc. was involved in an aviation accident near Brentwood, CA. Investigators recorded the probable cause as: 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. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 2 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-10Data APIEditorial standards

A helicopter rolled over after a student pilot made a large forward cyclic input while the instructor was focused on the collective friction setting; no mechanical failures reported.

Accident Overview

A helicopter collided with terrain and rolled over while hovering above flat terrain during a training exercise. The student pilot was practicing hover techniques by manipulating the flight controls individually. While the student was operating the cyclic, the certified flight instructor (CFI) noticed that the friction setting on the collective had been engaged.

Sequence of Events

As the CFI directed attention to the collective friction setting, the student made a large forward cyclic input. The helicopter responded by assuming an extreme nose-down attitude. The CFI then attempted to counteract the student's abrupt maneuver. Despite the instructor's efforts, the helicopter impacted the terrain and rolled over the nose, coming to rest on its right side.

Investigation Findings

The CFI reported that there were no preimpact mechanical malfunctions or failures with the helicopter. The accident occurred during a routine hover training session, with the student focused on individual control inputs and the instructor momentarily occupied with adjusting the collective friction.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20040622X00851. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.