Skip to content

Atlas / NTSB / WPR10CA442

NTSB CAROL · Event

Event WPR10CA442

2010-08-31 Caldwell, Idaho, United States Airport · EUL None 1 aircraft Status: Completed

Aircraft involved

Probable cause & findings

The failure of both pilots to maintain adequate main rotor RPM, the flight instructor's delayed remedial actions, and inadequate supervision of the flight.

Factual narrative

The purpose of the flight was for the helicopter-rated instructor pilot receiving instruction to become more familiar with the accident make and model helicopter. The intention of the flight instructor giving instruction was to demonstrate an autorotation on takeoff at low altitude, with the student following along on the controls. After ascending to an altitude of about 150 feet and an airspeed of about 50 knots, the instructor explained to the student that he was going to lower collective, but would not add cyclic to maintain airspeed. The instructor stated, “I lowered collective and could feel him [the student] on the collective, so I knew he was there. I then put right pedal in, split the needles, and then felt him [the student] pull back on the cyclic and pull up on the collective. I said ‘…no, push down,’ and I forced the cyclic forward.” The flight instructor said that the rotor RPM had by then decayed outside of normal parameters and that the student kept pulling up on the collective. “I tried to roll on power and force the cyclic forward, but we were descending too fast.” The student stated that during the demonstration he looked down at the rotor RPM and noticed that it was about 320 RPM, and that it stayed that low as the helicopter approached the ground. The student stated that he repeatedly told him [the flight instructor giving instruction] “low RPM" at least 5 times. The student added that after the hard landing the instructor told him that he [the student] had grabbed the controls because the helicopter didn’t pitch forward like he had intended it to do. The student stated, “I told him I hadn’t touched any of the controls and the reason he had no control was probably because the rotor RPM was so low.” An examination of the airframe by a Federal Aviation Administration inspector did not reveal any pre-impact anomalies. Additionally, neither pilot reported a malfunction of the airframe or engine. The purpose of the flight was for the helicopter-rated instructor pilot receiving instruction to become more familiar with the accident make and model helicopter. The intention of the flight instructor giving instruction was to demonstrate an autorotation on takeoff at low altitude, with the student following along on the controls. After ascending to an altitude of about 150 feet and an airspeed of about 50 knots, the instructor explained to the student that he was going to lower collective, but would not add cyclic to maintain airspeed. The instructor stated, “I lowered collective and could feel him [the student] on the collective, so I knew he was there. I then put right pedal in, split the needles, and then felt him [the student] pull back on the cyclic and pull up on the collective. I said ‘…no, push down,’ and I forced the cyclic forward.” The flight instructor said that the rotor RPM had by then decayed outside of normal parameters and that the student kept pulling up on the collective. “I tried to roll on power and force the cyclic forward, but we were descending too fast.” The student stated that during the demonstration he looked down at the rotor RPM and noticed that it was about 320 RPM, and that it stayed that low as the helicopter approached the ground. The student stated that he repeatedly told him [the flight instructor giving instruction] “low RPM" at least 5 times. The student added that after the hard landing the instructor told him that he [the student] had grabbed the controls because the helicopter didn’t pitch forward like he had intended it to do. The student stated, “I told him I hadn’t touched any of the controls and the reason he had no control was probably because the rotor RPM was so low.” An examination of the airframe by a Federal Aviation Administration inspector did not reveal any pre-impact anomalies. Additionally, neither pilot reported a malfunction of the airframe or engine. 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 Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Prop/rotor parameters-Not attained/maintained - C
  • C Personnel issues-Psychological-Attention/monitoring-Monitoring other person-Instructor/check pilot - C
  • C Personnel issues-Action/decision-Action-Delayed action-Instructor/check pilot - C

Verbatim from NTSB's published report. Source file NTSB_2010_WPR10CA442.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.