# NTSB CEN20LA136: Robinson Helicopter R44 II, N107EH, Audubon, IA, March 31, 2020 - Type: NTSB accident investigation - Classification: Accident · Fatal · Class 3 · Limited · Final report - Date: March 31, 2020, 16:26 local (21:26 UTC) - Place: Audubon, IA - Coordinates: 41.659911, -94.763558 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.6599&lon=-94.7636&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Controlled flight into terr/obj (CFIT)](https://openairdocs.org/ntsb-events/120) - Highest injury: Fatal - Injuries: 2 fatal - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA - Des Moines FSDO - NTSB case key (mKey): 101136 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN20LA136 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101136/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101136 - Page: https://openairdocs.org/ntsb/CEN20LA136 ## Probable cause The pilot’s failure to recognize and avoid the power line during the low-altitude flight. Contributing to the accident was the pilot’s fatigue, which affected the pilot’s ability to see and avoid the power line. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Object/animal/substance: wire](https://openairdocs.org/ntsb-findings/03022032): Environmental issues › Physical environment · Effect on operation (probable cause); cases with it: [Robinson Helicopter R44 II, 26 cases](https://openairdocs.org/ntsb-findings/03022032/cases.md?model=7640122), [All aircraft, 588 cases](https://openairdocs.org/ntsb-findings/03022032/cases.md) - [Alertness/Fatigue: fatigue due to work schedule](https://openairdocs.org/ntsb-findings/02013520): Personnel issues › Physical · Pilot (probable cause); cases with it: [Robinson Helicopter R44 II, 1 case](https://openairdocs.org/ntsb-findings/02013520/cases.md?model=7640122), [All aircraft, 25 cases](https://openairdocs.org/ntsb-findings/02013520/cases.md) - [Info processing/decision: identification/recognition](https://openairdocs.org/ntsb-findings/02041510): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Robinson Helicopter R44 II, 10 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md?model=7640122), [All aircraft, 559 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Controlled flight into terr/obj (CFIT)](https://openairdocs.org/ntsb-events/120) (defining event); cases with it: [Robinson Helicopter R44 II, 12 cases](https://openairdocs.org/ntsb-events/120/sequence.md?model=7640122), [All aircraft, 1,074 cases](https://openairdocs.org/ntsb-events/120/sequence.md) ## Analysis The pilot and passenger were conducting a low-altitude raptor survey flight. Witnesses reported seeing the helicopter flying just prior to its impact with powerlines about 85 ft above the ground. The witnesses described the helicopter in a gentle turn toward the sun prior to impact. One witness noted that he did not hear any unusual noises from the helicopter prior to impact. Automatic dependent surveillance-broadcast data from the helicopter provided information indicating the pilot flew six flights in the 24 hours prior to the accident. The accident flight was the fifth that day and occurred approximately 10 hours after the pilot had begun flying that morning. Intervals between flights that day were 17, 24, 35, and 29 minutes. These working conditions were conducive to fatigue. Research on pilot fatigue in a noisy, vibrating helicopter simulator found considerable increases in subjective fatigue after 6 hours of short repetitive flights. At the end of this period, some helicopter pilots who participated in the study said they were so fatigued that they did not feel safe to fly a real helicopter. As subjective fatigue increased, study pilots demonstrated increasingly frequent “lapses” in performance. While missions the day of the accident were longer than those in the study, flights were conducted at low altitude and involved repetitive observation tasks that required a high state of awareness to avoid terrain and obstacles. This heightened state of awareness would produce a mental workload similar to the shorter repetitive IFR flights in the study; therefore, it is likely that similar effects would be expected, including lapses in performance as fatigue increased. These lapses in performance were described in the study as outliers caused by moments of inattention. The accident pilot’s ability to avoid the same wire nine times earlier that day, but not avoid it during the accident flight is consistent with an attentional “lapse.” This potential lapse combined with over 10 hours since awakening, and 8 hours flight time already accumulated the day of the accident suggests that the pilot was likely fatigued during the accident flight and that fatigue likely challenged the pilot’s ability to see and avoid the power line. ## Factual narrative On March 31, 2020, about 1626 central daylight time, a Robinson R44 helicopter, N107EH, was destroyed when it was involved in an accident near Audubon, Iowa. The pilot and passenger were fatally injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 aerial observation flight. According to the operator, the purpose of the flight was to conduct a raptor survey of a 442 square-mile area in western Iowa under contract with another company whose biologist was the passenger on the helicopter at the time of the accident. The helicopter was flying a north-south grid pattern when two witnesses observed the helicopter flying in a southerly direction at low altitude. One witness observed the helicopter strike the bottom two wires of a power line before it impacted terrain and burst into flames. The second witness lost sight of the helicopter just before it impacted the wires but heard the impact and observed the helicopter descend with wires intertwined in the main rotor. Both witnesses thought the helicopter was in a turn to the southwest, toward the sun, prior to the hitting the wires. One witness described the helicopter in a gentle turn, not in a way that looked like the pilot was aware of the high lines. Automatic dependent surveillance- broadcast (ADS-B) data showed that during the final moments of the accident flight, the helicopter was travelling south over Robin Avenue, approaching 240th Street, at an ADS-B-reported geometric altitude of 1,475 ft, with a ground speed of about 85 kts. The final recorded data point was about 160 ft north of the wires that were struck. There were no deviations in heading or altitude before the end of the data. The ground elevation at the accident site was about 1,460 ft. The flights within the survey area were conducted at altitudes about 100 ft above the ground. Examination of the flight track data for the previous flight showed that the helicopter had crossed the power lines on at least two occasions during the previous flight. (See Figure 1.) Based on ADS-B flight data and the pilot’s flight records, he had flown a flight the night prior to the accident that concluded in the Sioux Falls, South Dakota, area, lasted about 45 minutes, and was followed by about 9 hours of non-flight activity. It is not known what the pilot did during this time of non-flight activity. On the day of the accident the pilot flew five flights lasting 51 minutes, 18 minutes, 3 hours 29 minutes, 3 hours 11 minutes, and 22 minutes, respectively. The first flight of the day took off at 0629. Between these flights were periods of non-flight activity lasting 17 minutes, 24 minutes, 35 minutes and 29 minutes, respectively. It was reported that the biologist joined the flight after the helicopter arrived at Arthur N. Neu Airport (CIN), Carroll, Iowa, after the second flight of the day. Figure 1: Plot of the survey area and the helicopter flight path on the day of the accident. Figure 2: 3-dimensional view of thefinal portion of the accident flight path. The helicopter came to rest in a field next to the west side of Robin Avenue and south of 240th Street. The wires that were struck ran along the north edge of 240th Street, strung between poles that were about 100 ft. tall. The estimated height of the wires struck was about 85 ft. above the ground. Figure 3. Location of powerlines, helicopter flight path, and wreckage. A post-impact fire consumed most of the cabin section of the helicopter. A postaccident examination of the helicopter after it was removed from the site revealed no preimpact anomalies. A large wire was found wrapped around the rotor mast just below the main rotors. Figure 4: Powerline wires wrapped around main rotor mast. ## Aircraft - Registration: [N107EH](https://openairdocs.org/deregistered/N107EH-2023-03-04), registration cancelled 2023-03-04, S/N 10423 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER COMPANY R44 II (II) - Registry model: [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii) (registry code 7640122) (OpenAirDocs) - Category: Helicopter - Serial number: 10423 - Year built: 2004 - Airframe hours: 1906 - Engines: Lycoming IO-540-AE1A5 245 horsepower reciprocating - Damage: Destroyed - Fire: On-Ground - Flight: Aerial observation, Part 91 - Operator: Ride the Sky Helicopters - Registered owner: MN Helicopters Inc. - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 27, 2020 - Departed: CIN, Carroll, IA - Equipment: ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 30; injuries: fatal; commercial; medical: class 2, without waivers/limitations; toxicology performed; flight hours: 952.9 total, 665 in this make and model, 897.6 as pilot in command, 68 in the last 90 days, 14 in the last 30 days, 9.5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 0° at 0 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 68 °F, dew point 18 °F - Altimeter: 29.95 inHg - Observed at: ADU, 7 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20200331002989A](https://openairdocs.org/incident/20200331002989A), Mar 31, 2020: Robinson Helicopter Company R44 II, Audubon, IA, Destroyed, 2 fatal. A Robinson R44 ii helicopter flying level at low altitude, 85-90 feet AGL, contacted the bottom two lines of a power transmission, high voltage, line. The… ## Docket (15 files) The files NTSB released with the investigation on February 9, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101136. 71.9 MB in all. - Pilot flight records and information (item 1, PDF, 39 pages, 26.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13088506&FileExtension=pdf&FileName=Pilot%20flight%20info_Redacted-Rel.pdf - Witness statements (item 2, PDF, 2 pages, 263 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13089198&FileExtension=pdf&FileName=Witness%20Statements_Redacted-Rel.pdf - FAA record of conversation with witnesses (item 3, PDF, 3 pages, 135 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13089105&FileExtension=pdf&FileName=FAA%20Record%20of%20conversation%20with%20Witnesses_Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 4, PDF, 1 page, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13088948&FileExtension=pdf&FileName=Signed%20wreckage%20release_Redacted-Rel.pdf - Weather METAR data (item 5, PDF, 2 pages, 84 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13089208&FileExtension=pdf&FileName=Weather%20METARS-Rel.pdf - Airframe maintenance records (item 6, PDF, 12 pages, 15.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13093779&FileExtension=pdf&FileName=N107EH%20Aircraft%20Logbook_Redacted-Rel.pdf - Engine maintenance records (item 7, PDF, 11 pages, 15.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13093967&FileExtension=pdf&FileName=N107EH%20Engine%20Logbook_Redacted-Rel.pdf - Photo array (item 8, PDF, 11 pages, 11 photos, 4.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13125096&FileExtension=pdf&FileName=Photo%20array-Rel.pdf - Autopsy memorandum (item 9, PDF, 1 page, 119 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13095340&FileExtension=pdf&FileName=Autopsy%20Memo-Rel.pdf - Toxicological report (item 10, PDF, 1 page, 333 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13095031&FileExtension=pdf&FileName=2020_051_001_Redacted-Rel.pdf - ADS-B data (courtesy of FAA) (item 11, CSV, 5.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13103756&FileExtension=csv&FileName=20200331_N107EH_%20A01F21_Daily-Rel.csv - Plotted ADS-B data (accident flight) (item 12, KMZ, 18 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13103335&FileExtension=kmz&FileName=Accident%20Flight-Rel.kmz - Plotted ADS-B data (previous flights) (item 13, KMZ, 483 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13103673&FileExtension=kmz&FileName=Prior%20flights-Rel.kmz - Accident flight plots (item 14, PDF, 2 pages, 680 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13103683&FileExtension=pdf&FileName=CEN20LA136%20Plots-Rel.pdf - Wreckage exam summary (item 15, PDF, 5 pages, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13199006&FileExtension=pdf&FileName=Examination%20summary-Rel.pdf From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.