Accident General Atomics MQ-9A Reaper 12-4175,
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ASN Wikibase Occurrence # 210605
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Date:Saturday 6 May 2017
Time:22:38 UTC
Type:Silhouette image of generic Q9 model; specific model in this crash may look slightly different    
General Atomics MQ-9A Reaper
Owner/operator:US Air Force (USAF)
Registration: 12-4175
Fatalities:Fatalities: 0 / Occupants: 0
Aircraft damage: Written off (damaged beyond repair)
Location:Middle East -
Phase: Approach
Departure airport:
Destination airport:
Investigating agency: USAF AIB
Confidence Rating: Accident investigation report completed and information captured
On 6 May 2017, at about 22:38 Zulu Time (Z), the mishap aircraft (MA), an MQ-9A, tail number 12-4175, assigned to the 432d Wing (432 WG), and operated by the 361st Expeditionary Reconnaissance Squadron (361 ERS), 332d Air Expeditionary Wing (332 AEW), crashed in the United States Central Command Area of Responsibility after MA handover from the Mission Control Element (MCE) to the Launch and Recovery Element (LRE). The MA was destroyed following impact with terrain and no wreckage was recovered.

At about 2003Z, the LRE mishap crew (MC) gained control of the MA. The MC consisted of the mishap pilot (MP), the mishap instructor pilot, and the mishap sensor operator. After handover, the MC ran through standard checklists. In accordance with the checklists, the MP updated the emergency mission (EM) start point and attempted to send the EM to the MA. The MP elected to power down the Interim Modem Assembly (IMA) before landing, which severed the MA’s link to the MCE. At about 2025Z, the Ground Control Station lost downlink from the MA on final approach to the airfield due to interference by another MQ-9A transmitting on high power on the ground. As a result, the MC lost situational awareness of the MA.
Approximately one minute after the loss of downlink, the MC terminated uplink in accordance with emergency procedures, which caused the MA to execute its EM. The MP’s attempt to send the LRE EM to the MA, as required after handover, was unsuccessful. Therefore, the MA executed the last EM received from the MCE. In accordance with the MCE EM, the MA flew away from the airfield with its downlink transmitters disabled. Despite efforts, neither the LRE nor MCE could recover link to the MA. The MCE crew did not delete any EM waypoints before handover to LRE. As a result, the MA had insufficient fuel to fly through all EM waypoints before returning to the LRE airfield. The MA crashed while executing the MCE EM two hours and 13 minutes after losing downlink.

The Abbreviated Accident Investigation (AAIB) President found by a preponderance of the evidence that the causes of the mishap were: (1) the unintentional downlink interference from a ground-based MQ-9A transmitting on high power, and (2) the failure to successfully send an LRE EM to the MA after handover from the MCE. The AAIB President found by a preponderance of the evidence that factors that substantially contributed to the mishap were: (1) the LRE practice of disabling the IMA before landing, and (2) the MCE practice of not deleting EM waypoints before LRE handover.


Accident investigation:
Investigating agency: USAF AIB
Report number: 
Status: Investigation completed
Duration: 1 year
Download report: Final report

Revision history:

08-May-2018 06:41 plcedi Added
09-May-2018 19:54 Aerossurance Updated [Operator, Source, Narrative]
24-Aug-2018 07:37 harro Updated [Time, Registration, Source, Narrative]

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