# NTSB DCA12CA023: University Of Kansas Meridian, McMurdo, AY, December 19, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: December 19, 2011, 03:17 local (03:17 UTC) - Place: McMurdo, AY - Coordinates: -77, 166 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=-77.0000&lon=166.0000&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241) - Highest injury: No injuries - Status: Completed, report April 3, 2013 - Report: Approved by Office Director - NTSB office: Major Investigations Division - NTSB case key (mKey): 82580 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA12CA023 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/82580/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=82580 - Page: https://openairdocs.org/ntsb/DCA12CA023 ## Probable cause an aerodynamic stall induced by an inadvertent autopilot Home command. The Home command was entered following a loss of the direct radio link due to improperly set failsafe settings, and an unintentional latching of Home mode from an earlier functionality test. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Capability exceeded (probable cause); cases with it: [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md) - [Auto flight system: autopilot system](https://openairdocs.org/ntsb-findings/01022210): Aircraft › Aircraft systems · Incorrect use/operation (probable cause); cases with it: [All aircraft, 28 cases](https://openairdocs.org/ntsb-findings/01022210/cases.md) - [Auto flight system: autopilot system](https://openairdocs.org/ntsb-findings/01022210): Aircraft › Aircraft systems · Unintentional use/operation (probable cause); cases with it: [All aircraft, 28 cases](https://openairdocs.org/ntsb-findings/01022210/cases.md) - [Selection/certification/testing: equip certification/testing](https://openairdocs.org/ntsb-findings/04012015): Organizational issues › Development · Operator (probable cause); cases with it: [All aircraft, 21 cases](https://openairdocs.org/ntsb-findings/04012015/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241) (defining event); cases with it: [All aircraft, 1,529 cases](https://openairdocs.org/ntsb-events/241/sequence.md) - [Landing: Hard landing](https://openairdocs.org/ntsb-events/092); cases with it: [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) ## Analysis On December 20, 2011, at 1517 local time (0317, December 19, Coordinated Universal Time (UTC)), an experimental Meridian unmanned aerial system (UAS), built, owned, and operated by the University of Kansas under a National Science Foundation grant, crashed on final approach to the Pegasus Ice Runway at McMurdo Station, Antarctica. The aircraft was substantially damaged, and there were no injuries or ground damage. The aircraft was returning from a flight test in which the airplane was controlled via an over-the-horizon satellite (Iridium) control link. Approximately 60 seconds prior to the accident, the pilot took over direct control of the aircraft via 72MHz radio control (similar to a model airplane). On final approach, as the aircraft was commanded low power and nose down pitch, the aircraft lost the 72MHz link, and as programmed the flight control system switched to an autopilot Manual (Assisted) mode. The Manual (Assisted) mode commanded the aircraft to predefined “failsafe” settings of 100 knots airspeed and neutral controls, resulting in about 27 degrees of nose up pitch change. After about one second, the control mode was changed from the failsafe setting to the Home mode, which was inadvertently left latched due to a functionality test earlier in the flight. The Home mode commanded the airplane to climb toward the home waypoint, which was over the runway, and enter an orbit. The airplane was well below the home altitude and at low airspeeds for approach. The command resulted in a power-on stall and steep nose down descent. Radio control link was re-established but too late to recover from the stall. The airplane impacted the ice runway and was substantially damaged. ## Factual narrative On December 20, 2011, at 1517 local time (0317, December 19, Coordinated Universal Time (UTC)), an experimental Meridian unmanned aerial system (UAS), built, owned, and operated by the University of Kansas under a National Science Foundation grant, crashed on final approach to the Pegasus Ice Runway at McMurdo Station, Antarctica. The aircraft was substantially damaged, and there were no injuries or ground damage. The aircraft was returning from a flight test in which the airplane was controlled via an over-the-horizon satellite (Iridium) control link. Approximately 60 seconds prior to the accident, the pilot took over direct control of the aircraft via 72MHz radio control (similar to a model airplane). On final approach, as the aircraft was commanded low power and nose down pitch, the aircraft lost the 72MHz link, and as programmed the flight control system switched to an autopilot Manual (Assisted) mode. The Manual (Assisted) mode commanded the aircraft to predefined “failsafe” settings of 100 knots airspeed and neutral controls, resulting in about 27 degrees of nose up pitch change. After about one second, the control mode was changed from the failsafe setting to the Home mode, which was inadvertently left latched due to a functionality test earlier in the flight. The Home mode commanded the airplane to climb toward the home waypoint, which was over the runway, and enter an orbit. The airplane was well below the home altitude and at low airspeeds for approach. The command resulted in a power-on stall and steep nose down descent. Radio control link was re-established but too late to recover from the stall. The airplane impacted the ice runway and was substantially damaged. ## Aircraft - Registration: UNREG (not matched to a registry record) - Reported make and model: UNIVERSITY OF KANSAS MERIDIAN - Category: Airplane, amateur-built, unmanned - Serial number: 1 - Airframe hours: 10 - Engines: TAE Centurion 1.7 135 horsepower reciprocating - Damage: Substantial damage - Flight: Flight test, Non-U.S., non-commercial - Operator: University of Kansas - Registered owner: University of Kansas - Airworthiness certificate: Unknown - Departed: NZPG, McMurdo - Destination: NZPG, McMurdo - Airport: NZPG, Pegasus McMurdo, Antarctica, runway 33, 10,000 × 200 ft, ice ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 23; injuries: none; medical: unknown; flight hours: 10 total, 10 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 360° at 9 knots ## Docket (4 files) The files NTSB released with the investigation on April 3, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=82580. 5.6 MB in all. - Operator Aircraft Accident Report - Initial (item 1, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40379584&FileExtension=.PDF&FileName=Operator%20Aircraft%20Accident%20Report%20-%20Initial-Master.PDF - Reports from Parties to the Investigation - Review Presentation (item 2, .PDF, 2.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40379586&FileExtension=.PDF&FileName=Reports%20from%20Parties%20to%20the%20Investigation%20-%20Review%20Presentation-Redacted.PDF - Operations 2 - Antarctica CONOPS (item 3, .PDF, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40379595&FileExtension=.PDF&FileName=Operations%202%20-%20Antarctica%20CONOPS-Master.PDF - Operations 2 - Test Card (item 4, .PDF, 93 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40379596&FileExtension=.PDF&FileName=Operations%202%20-%20Test%20Card-Master.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.