What happened
On 18:00LT on 19 July 2024, a Hexadrone Tundra 2 (Urban) was being used for a flight test from a rooftop in a populated area. The aircraft was part of a series of tests being conducted by H3 Dynamics to develop a remote Command Centre System (C2). During the eighth flight of the day, shortly after takeoff, the unmanned aircraft began flying in an erratic manner, deviating from its pre-programmed mission path.
The pilot on the rooftop and a remote operator attempted several maneuvers to regain control, including switching the flight computer to various modes such as LOITER and ALT_HOLD. Despite these efforts, the aircraft could not be stabilized. The drone eventually breached its established geofence and traveled approximately 200m away from the operational area. At approximately 85 seconds after takeoff, the aircraft struck a residential building, causing it to fall to the ground near a pedestrian. The impact was followed by a fire that destroyed the aircraft. There were no injuries to any persons.
The investigation
The investigation focused on the flight logs, the C2 system interface, and the modifications made to the aircraft. Investigators examined the integration of a companion computer used to allow remote control via the internet. The inquiry also reviewed the regulatory compliance of the operator, specifically regarding the definition of "operational control" and the necessity of pilot licenses for remote system operators. Additionally, the investigation looked into the accuracy of the documentation provided to the regulator regarding the aircraft's features and its modification status.
Findings
- The investigation could not determine the specific reason for the erratic flight behavior or why the flight computer's failsafe Return to Launch (RTL) function failed to perform as expected, due to the destruction of the aircraft by fire.
- The operator had integrated a companion computer to enable remote monitoring and control but did not classify this as a significant modification requiring regulatory notification.
- The remote system operator was performing functions involving operational control without holding a required Unmanned Aircraft Pilot Licence (UAPL).
- There was a discrepancy in the operational manual regarding a motor power-cut feature that was not actually present on the aircraft.
Safety action
Following the incident, the regulator implemented several changes, including an on-site audit program for large-scale operators and updated guidance for permit applications. New flight test categories were introduced to better manage varying risk levels, and the regulator clarified the requirements for updating permits when aircraft configurations are changed.