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Atlas / NTSB / GAA17CA434

NTSB CAROL · Event

Event GAA17CA434

2017-07-21 Bozeman, Montana, United States Airport · BZN None 1 aircraft Status: Completed

Aircraft involved

Probable cause & findings

The flight instructor’s unstabilized autorotation, which resulted in a hard landing.

Factual narrative

According to the helicopter flight instructor, he was demonstrating simulated 180° right turn autorotations. He reported that during the entry of the third autorotation, the helicopter attitude was excessively nose low and the rate of descent was high. He initiated a power-on recovery; however, the flare was initiated too late. He applied forward cyclic to level the skids and increased collective to its mechanical limit, but the helicopter touched down and one of the main rotor blades struck the tailboom. The helicopter sustained substantial damage to the tailboom. The pilot reported in the National Transportation Safety Board's, Pilot Aircraft Accident Report, "The event could have been avoided by recovering the autorotation sooner and doing a go-around." The operator reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation. According to the helicopter flight instructor, he was demonstrating simulated 180° right turn autorotations. He reported that, during the entry of the third autorotation, the helicopter attitude was excessively nose low and the descent rate was high. He initiated a power-on recovery; however, the flare was initiated too late. He applied forward cyclic to level the skids and increased collective to its mechanical limit, but the helicopter touched down hard, and one of the main rotor blades struck the tailboom. The helicopter sustained substantial damage to the tailboom. The pilot reported in the National Transportation Safety Board's Pilot Aircraft Accident Report, "The event could have been avoided by recovering the autorotation sooner and doing a go-around." The operator reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation. Source: NTSB Aviation Accident Database Retrieved: 2026-02-12

NTSB Findings

Hierarchical cause / factor breakdown from the FAA bulk avdata database. Each finding tagged C (Cause) or F (Factor).

  • C Personnel issues-Task performance-Use of equip/info-Aircraft control-Instructor/check pilot - C
  • C Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Descent rate-Not attained/maintained - C
  • C Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Prop/rotor parameters-Not attained/maintained - C

Verbatim from NTSB's published report. Source file NTSB_2017_GAA17CA434.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.

Related research

What the literature says.

Academic papers and agency reports matching this event's aircraft type or causal vocabulary (go-around). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.

Browse the full corpus — academia portal ↗