Accident General Atomics MQ-9A Reaper 08-4035,
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ASN Wikibase Occurrence # 223845
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Date:Wednesday 10 April 2019
Type:Silhouette image of generic Q9 model; specific model in this crash may look slightly different    
General Atomics MQ-9A Reaper
Owner/operator:United States Air Force (USAF)
Registration: 08-4035
Fatalities:Fatalities: 0 / Occupants: 0
Aircraft damage: Written off (damaged beyond repair)
Location:Helmand province -   Afghanistan
Phase: Combat
Departure airport:
Destination airport:
Investigating agency: USAF AIB
Confidence Rating: Accident investigation report completed and information captured
On 10 April 2019, at about 0200 UTC, the mishap aircraft (MA), an MQ-9A, tail number 08-4035, departed controlled flight and impacted the terrain in an undisclosed location within the United States Central Command (US CENTCOM) Area of Responsibility (AOR) *.
Assigned to the 432d Wing, Creech Air Force Base (AFB), Nevada, the MA was operated by the 42d Attack Squadron Mission Control Element located at Creech AFB, Nevada, at the time of the mishap. The MA wreckage was located and destroyed.
At about 0156Z, several control inputs from the mishap Ground Control Station (MGCS) to the MA changed simultaneously. Among these commands was an input to close the fuel shut-off valve and feather the propeller. Over the next minute, the MA’s engine torque, oil pressure, and propeller speed decreased, as the engine shutdown. In accordance with the emergency procedures checklist, the mishap crew (MC), consisting of the mishap pilot (MP) and mishap sensor operator (MSO), performed engine failure procedures. Since the MA continued to receive erroneous commands, which kept the fuel shut-off valve closed for the remainder of the mishap flight, the engine remained shut down and could not be restarted.
The MGCS sent erroneous pitch, roll, and yaw commands, but the MA initially ignored them because autopilot hold modes were enabled. When hold modes were disabled to permit emergency checklist accomplishment, the MA began executing the erroneous pitch, roll, yaw stick, and rudder commands from the MGCS. The MC performed emergency checklist procedures to prevent loss of control, but they were unable to recover the MA. The rapid changes in MA attitude resulting from the erroneous control inputs caused intermittent departures from controlled flight and a permanent loss of datalink. Subsequently, the MA impacted the ground at an undisclosed location within the USCENTCOM AOR and the MA wreckage was destroyed.
The Abbreviated Accident Investigation Board (AAIB) President found, by a preponderance of the evidence, the cause of the mishap was a loose, flat metallic washer on the Control Console Serial Module (CCSM) that created an electrical short between several pins, resulting in erroneous control inputs being transmitted to the MA. Further, the AAIB President found, by a preponderance of the evidence, that each of the following factors substantially contributed to the mishap; (1) the design of the Control Console Assembly (CCA), which contains inadequately restrained metallic hardware, and (2) limitations in software fault logic.

* While the USAF did not reveal the accident location, an Afghan news agency reported that on April 10, 2019, a USAF UAV had crashed in Helmand Province.


Accident investigation:
Investigating agency: USAF AIB
Report number: 
Status: Investigation completed
Download report: Final report

Revision history:

10-Apr-2019 06:43 gerard57 Added
05-Sep-2020 12:19 harro Updated [Aircraft type, Registration, Operator, Source, Narrative, Accident report, ]

Corrections or additions? ... Edit this accident description

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