CEN10LA556
2010-09-17 · Duluth, Minnesota, United States · Minor · 1 aircraft · Status: Completed
Airport DLH
N145DM has since been reassigned. It is now registered to a different aircraft (AIRBUS HELICOPTERS INC MBB-BK117 D-3), which was not involved in this event.
Aircraft involved
Probable cause & findings
The pilot's failure to identify and arrest the helicopter's descent due to spatial disorientation.
Factual narrative
On September 17, 2010, about 0023 central daylight time, a Robinson R44 II helicopter, N145DM, piloted by a commercial pilot, was destroyed during an in-flight collision with the waters of Island Lake near Duluth, Minnesota. The flight was being conducted under 14 Code of Federal Regulations Part 91 without a flight plan. Night visual meteorological conditions prevailed. The pilot sustained minor injuries. The flight departed from a beach on Island Lake and was on the initial climbout at the time of the accident. The intended destination was Duluth International Airport (DLH), Duluth, Minnesota, which was located about 10 miles south of the accident site. The pilot reported that he had flown from DLH to the beach site on Island Lake in order to show the helicopter to some prospective clients. After spending several hours, he decided to return to DLH. The pilot stated that he lifted off into a hover, and subsequently established a 600 foot-per-minute rate of climb at 60 knots airspeed to depart the area. As he climbed out, he reported a "sinking feeling in the seat all of a sudden," and noticed that the vertical speed indicator "started to dip down indicating a descent." His flight instruments indicated that the helicopter was at 60 knots airspeed and in level flight; "everything checked out." He increased engine power, but was still descending. The pilot referenced the flight instruments a second time and noted that "all indications showed level and 60 [knots]." He recalled thinking that the helicopter might have encountered a "microburst of some type." He added that he could not tell the helicopter's exact height above the water because of the night lighting conditions. The helicopter hit the water at about 60 knots. The pilot commented that he thought the helicopter was still higher off the water and, as a result, did not flare prior to impact. A witness reported that the start and warm up were unremarkable. In addition, the liftoff and initial climb also appeared normal. He stated, "If the entire event took 10 seconds, only the last 2, showed concern as we could see the distance between the [helicopter's navigation] lights and the reflection in the water markedly become closer, ultimately converging." He noted that the helicopter appeared to be level and remain in controlled flight the entire time. A post accident examination of the helicopter did not reveal any anomalies consistent with a pre impact failure or malfunction. Weather conditions recorded at DLH, located about 10 miles south of the accident site, at 2355, included: Scattered clouds at 11,000 feet above ground level (agl), 10 miles visibility, and winds from 180 degrees at 4 knots. At 0055, conditions included: Broken clouds at 10,000 feet agl, 10 miles visibility, and wind from 240 degrees at 7 knots. The moon set at 0058, about 35 minutes after the accident. It was in a waxing gibbous phase, with 73 percent of the visible disk illuminated. The witness commented that the "night was dark, but there was a distinguishable horizon." He did not feel that the conditions were "adverse" for the pilot's return flight. The pilot informed Federal Aviation Administration (FAA) inspectors that he had executed a similar type of night departure in June; although, the night of the accident was darker. The pilot did not hold an instrument rating. However, he was reportedly working toward the rating and he had accumulated about 30 hours of instrument flight time. According to the pilot, he lifted the helicopter into a hover and subsequently established a 600 foot-per-minute rate of climb at 60 knots airspeed to depart the area. As the helicopter climbed out, he reported a sinking feeling in the seat and noticed that the vertical speed indicator displayed a descent. The pilot increased the engine power but the helicopter continued to descend. The pilot could not discern his exact height above the water because of the night lighting conditions and thought that the helicopter was higher off the water than it was; as a result, he did not flare prior to impact. A witness reported that the liftoff and initial climb also appeared normal and that the helicopter appeared to be level and remain in controlled flight the entire time. A postaccident examination of the airframe and engine revealed no mechanical malfunctions or failures that would have precluded normal operation. The witness commented that the conditions were dark at the time of the accident, but there was a distinguishable horizon. The light wind reported at the time of the accident and lack of convective activity in the area is inconsistent with a downdraft or microburst condition. Source: NTSB Aviation Accident Database Retrieved: 2026-02-12
NTSB Findings
FAA avdata. C = Cause, F = Factor.
- C Personnel issues-Psychological-Perception/orientation/illusio-Spatial disorientation-Pilot - C
- C Personnel issues-Action/decision-Action-Lack of action-Pilot - C
- — Environmental issues-Conditions/weather/phenomena-Light condition-Dark-Effect on operation
Verbatim from NTSB's published report. Source file
NTSB_2010_CEN10LA556.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
Matched on aircraft type or causal vocabulary (spatial disorientation, microburst). All research papers
- Embry-Riddle Scholarly Commons 2025 · Journal article (IJAAA) Design, Implementation, and Testing of Spatial Disorientation Scenarios in a Modified Hexapod Motion Simulator
Abstract Investigations into aviation accidents aim to identify root causes and enhance safety. Despite advancements in safety measures, technology, and education, general aviation accident rates rema…
- AOPA Air Safety Institute 2022 · Safety advisor Safety Advisor: Spatial Disorientation
Safety advisor on the perceptual illusions that cause spatial disorientation: the leans, graveyard spiral, somatogravic and somatogyral illusions, false horizon, and Coriolis.
- NASA NTRS 2019 · Conference Paper Evaluation of Low Cost, User-Centered Alerting Devices for the Mitigation of Flight Crew Spatial Disorientation
The National Aeronautics and Space Administration (NASA) is conducting research into technologies which have the potential to reduce flight crew Spatial Disorientation (SD).
- NASA NTRS 2019 · Conference Paper Optimal recovery from microburst wind shear
The flight path of a twin-jet transport aircraft is optimized in a microburst encounter during approach to landing. The objective is to execute an escape maneuver that maintains safe ground clearance …
- NASA NTRS 2019 · Presentation Pre-Flight Training of Autonomic Responses for Mitigating the Effects of Spatial Disorientation During Spaceflight
The National Aeronautics and Space Administration (NASA) has identified a potential risk of spatial disorientation, motion sickness, and degraded performance to astronauts during re-entry and landing …
- NASA NTRS 2019 · Other The Role of Spatial Disorientation in Fatal General Aviation Accidents
In-flight Spatial Disorientation (SD) in pilots is a serious threat to aviation safety. Indeed, SD may play a much larger role in aviation accidents than the approximate 6-8% reported by the National …