Loss of control Accident Bathawk ZT-UOZ, Friday 30 June 2023
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Date:Friday 30 June 2023
Time:22:16 UTC
Type:Bathawk
Owner/operator:
Registration: ZT-UOZ
MSN: B0017
Total airframe hrs:1242 hours
Fatalities:Fatalities: 0 / Occupants: 0
Other fatalities:0
Aircraft damage: Substantial
Category:Accident
Location:Westonaria Ward 1 -   South Africa
Phase: En route
Nature:Survey
Departure airport:Main Road, Westonaria Ward 1
Destination airport:Main Road, Westonaria Ward 1
Investigating agency: CAA S.A.
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The unmanned aircraft system (UAS) with registration ZT-UOZ was launched for surveillance operation at Transnet Freight Rail (TFR) in Westonaria Ward 1, Gauteng province. Visual meteorological conditions (VMC) prevailed at the time of the flight.
The pilot reported that he arrived on site and conducted the necessary checks on the UAS, and it was serviceable. At 1911Z, he launched the UAS for the first surveillance flight, which was successful. Upon the UAS’s return to the launch site, the pilot conducted post-flight inspection and changed the battery in preparation for the next flight. The battery power indicated 98% at the time of launch. The UAS climbed to a height of 400 feet (ft) above ground level (AGL) with the wind speed at 15 knots (kts) from the south. At 2111Z, the pilot switched to Auto mode and started the mission. The flight continued for approximately 55 minutes without incident. The remote pilot station did not show any warning signs of the UAS’s failure. During the flight, the wind had increased to 21 kts and the UAS heading was approximately 100 degrees.
According to the Bathawk User Manual, the UAS maximum operating wind is 12.5 m/s (24 kts). The pilot noticed that the UAS yawed and corrected itself repeatedly during the flight, and thus, decided to engage the return-to-launch function. The UAS headed to the base station but when it was still a distance away, it descended to a height of 150 ft (AGL) (45 metres) and the pilot observed an increase in oscillations (back and forth movement in a regular rhythm) with a significant roll. The pilot engaged Loiter mode (assisted flight mode with position and altitude hold), however, the UAS could not maintain a level flight and it spun to the left then recovered, and thereafter, spun to the right before it impacted the terrain. The pilot and his colleagues dispatched to the last recorded location that was captured on the remote pilot station and found the UAS crashed approximately 360 metres north of the ground station. The UAS sustained substantial damage. No injuries were reported on the ground.

Probable Cause
The UAS experienced low airspeed due to the change in wind direction which increased the Angle of Attack, and thus, led to the stall.

Accident investigation:
cover
  
Investigating agency: CAA S.A.
Report number: CA18/2/3/10342
Status: Investigation completed
Duration: 4 months
Download report: Final report

Sources:

SACAA

Location

Revision history:

Date/timeContributorUpdates
23-Nov-2023 13:36 harro Added

Corrections or additions? ... Edit this accident description

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