# NTSB DCA13CA172: Nasa Ames Research Center Sierra, Beaufort Sea, AK, July 27, 2013 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: July 26, 2013, 18:15 local (Jul 27, 2013, 02:15 UTC) - Place: Beaufort Sea, AK - Coordinates: 71.474441, -149.636383 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Status: Completed, report September 1, 2015 - Report: Approved by Office Director - NTSB office: Major Investigations Division - Parties: FAA Fairbanks FSDO - NTSB case key (mKey): 87634 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA13CA172 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/87634/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=87634 - Page: https://openairdocs.org/ntsb/DCA13CA172 ## Probable cause continued operation into engine intake system icing conditions resulting in a loss of power; due to schedule pressure and an insufficient risk management process. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Damaged/degraded (probable cause); cases with it: [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md) - [Temp/humidity/pressure: conducive to carburetor icing](https://openairdocs.org/ntsb-findings/03031030): Environmental issues › Conditions/weather/phenomena · Effect on equipment (probable cause); cases with it: [All aircraft, 435 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md) - [Safety programs: adequacy of safety program](https://openairdocs.org/ntsb-findings/04035015): Organizational issues › Support/oversight/monitoring · Operator (probable cause); cases with it: [All aircraft, 24 cases](https://openairdocs.org/ntsb-findings/04035015/cases.md) - [Design: equipment design](https://openairdocs.org/ntsb-findings/04011010): Organizational issues › Development · Not specified (probable cause); cases with it: [All aircraft, 35 cases](https://openairdocs.org/ntsb-findings/04011010/cases.md) - [Scheduling: task scheduling/workload](https://openairdocs.org/ntsb-findings/04023030): Organizational issues › Management · Operator (probable cause); cases with it: [All aircraft, 4 cases](https://openairdocs.org/ntsb-findings/04023030/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis On July 26, 2013, approximately 18:50 Alaska Daylight Time, a National Aeronautics and Space Administration (NASA) Sensor Integration Evaluation Remote Research Aircraft (SIERRA) single-engine fixed wing unmanned aircraft system (UAS) was substantially damaged following an engine power loss and uncontrolled descent into the Beaufort Sea, 65 nautical miles north of Oliktok Point, Alaska. The flight was conducted as a non-military public aircraft operation under the provisions of Title 49 of the United States Code (U.S.C.) Sections 40102 and 40125, and a Federal Aviation Administration (FAA) Certificate of Authorization (COA). There were no injuries. The UAS was on it's maiden science flight for the Marginal Ice Zone Observations and Processes Experiment (MIZOPEX) and lost engine power 4.5 hours into the 6 hour scheduled flight. The UAS was powered by a 26 horsepower Herbrandson Dyad 290B 2-cycle carbureted engine with a belt driven pusher fixed pitch propeller. The flight crew noted a loss of engine RPM and electrical bus voltage on the CloudCap Piccolo Autopilot (AP) system display that was part of the ground control system (GCS). The UAS was beyond the range of the hand held radio and under the control of the Piccolo AP, upon losing power the GCS operator was unable to issue any commands to the aircraft. Telemetry data revealed that for a period of about 60 minutes prior to the accident, RPM and altitude fluctuated, and throttle demand increased, indicating the possibility of engine intake icing. Weather conditions at the time of the accident were included relative humidity (RH) from 85% to 95%, at 4 degrees C. The nearest observation sites to the accident were Deadhorse (62 km) and Nuiqsut (52 km). Both of these stations reported temperatures ranging from 9 to 14 degrees Celsius during the flight time. The National Center for Atmospheric Research examined the weather conditions and concluded a high risk for carburetor ice existed. The MIZOPEX Project was under significant time and budget constraints due to a change in project plan from a larger UAS platform requiring payload bay changes within the original funding timeline. A full NASA Mishap Investigation Team report of this accident is available in the public docket for this case. ## Factual narrative On July 26, 2013, approximately 18:50 Alaska Daylight Time, a National Aeronautics and Space Administration (NASA) Sensor Integration Evaluation Remote Research Aircraft (SIERRA) single-engine fixed wing unmanned aircraft system (UAS) was substantially damaged following an engine power loss and uncontrolled descent into the Beaufort Sea, 65 nautical miles north of Oliktok Point, Alaska. The flight was conducted as a non-military public aircraft operation under the provisions of Title 49 of the United States Code (U.S.C.) Sections 40102 and 40125, and a Federal Aviation Administration (FAA) Certificate of Authorization (COA). There were no injuries. The UAS was on its maiden science flight for the Marginal Ice Zone Observations and Processes Experiment (MIZOPEX) and lost engine power 4.5 hours into the 6 hour scheduled flight. The UAS was powered by a 26 horsepower Herbrandson Dyad 290B 2-cycle carbureted engine with a belt driven pusher fixed pitch propeller. The flight crew noted a loss of engine RPM and electrical bus voltage on the CloudCap Piccolo Autopilot (AP) system display that was part of the ground control system (GCS). The UAS was beyond the range of the hand held radio and under the control of the Piccolo AP, upon losing power the GCS operator was unable to issue any commands to the aircraft. Telemetry data revealed that for a period of about 60 minutes prior to the accident, RPM and altitude fluctuated, and throttle demand increased, indicating the possibility of engine intake icing. Weather conditions at the time of the accident were included relative humidity (RH) from 85% to 95%, at 4 degrees C. The nearest observation sites to the accident were Deadhorse (62 km) and Nuiqsut (52 km). Both of these stations reported temperatures ranging from 9 to 14 degrees Celsius during the flight time. The National Center for Atmospheric Research examined the weather conditions and concluded a high risk for carburetor ice existed. The MIZOPEX Project was under significant time and budget constraints due to a change in project plan from a larger UAS platform requiring payload bay changes within the original funding timeline. A full NASA Mishap Investigation Team report of this accident is available in the public docket for this case. ## Aircraft - Registration: UNREG (not matched to a registry record) - Reported make and model: NASA AMES RESEARCH CENTER SIERRA - Category: Airplane, unmanned - Serial number: 1 - Year built: 2013 - Engines: Herbrandson Dyad 290B reciprocating - Damage: Substantial damage - Flight: Aerial observation, Public use - Operator: NASA Ames Research Center - Registered owner: NASA Ames Research Center - Airworthiness certificate: Certificate of authorization or waiver (COA) - Departed: POLI, Oliktok Point, AK - Destination: POLI, Oliktok Point, AK - Flight plan: IFR - Equipment: Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 51; injuries: none; private; airplane ratings: single-engine land; medical: class 2; seat: none ## Weather - Conditions: Visual (VMC), Day - Wind: 20° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: 4,000 ft overcast - Temperature: 54 °F, dew point 45 °F - Altimeter: 30.10 inHg - Observed at: PASC, 82 nm away ## Docket (3 files) The files NTSB released with the investigation on January 20, 2015, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=87634. 6.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40421334&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - NASA Sierra Mishap Report (item 2, .PDF, 14 photos, 4.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40421336&FileExtension=.PDF&FileName=NASA%20Sierra%20Mishap%20Report-Redacted.PDF - FAA COA Report (item 3, .PDF, 591 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40421335&FileExtension=.PDF&FileName=FAA%20COA%20Report-Redacted.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.