History of the Flight
On 19 July 2024, an unmanned aircraft (UA) operated by H3 Dynamics was undergoing a flight test from the rooftop of a building in a built-up area. The UA was a Hexadrone Tundra 2 (Urban) quadcopter. The operator held an Operator Permit granted by the regulator. The flight test was part of the development of an online system called the Command Centre System (C2 system), which allowed remote control and monitoring of the UA via a laptop. Eight flights were planned for that day.
Persons Involved
Three persons were involved in the flight test:
- A UA pilot (UAP) on the rooftop, who could control the UA via a remote controller (RC).
- A C2 system operator (OPT1) at a remote location, who could control the UA via a C2 system user interface (C2 UI).
- Another C2 system operator (OPT2) on the rooftop, acting as a flight test observer, who monitored data feedback via another C2 UI and relayed messages between UAP and OPT1. OPT2 did not provide any input to the C2 system during the occurrence.
Sequence of Events
Before each flight, UAP set the Flight Control Computer (FCC) on board the UA to GUIDED mode using the RC. OPT1 would then upload a mission via the C2 UI and initiate the flight. The FCC would command the UA to take off and autonomously follow the mission route. UAP could take over control via the RC when necessary.
A geofence with a radius of 60m from the take-off position was defined using the RC. If the UA flew beyond this geofence, the FCC's Failsafe Function should automatically set the FCC to Return to Launch (RTL) mode, commanding the UA to return to the take-off position and land.
At about 1757 LT, OPT1 uploaded a mission for the eighth test flight. About two minutes later, the UA took off. Instead of flying towards the first waypoint, the UA flew erratically. UAP attempted to regain control by switching the FCC from GUIDED mode to LOITER mode using the RC, but the UA continued its erratic flight. UAP toggled between ALT_HOLD and LOITER modes several times over approximately 20 seconds, but could not regain control.
The UA flew beyond the rooftop and out of view of UAP and OPT2. UAP did not cut power to the motors, as he was concerned about hitting people or objects below. At 25 seconds after take-off, UAP switched back to GUIDED mode and instructed OPT1 via OPT2 to activate Return to Home (RTH) mode via the C2 UI. OPT1 complied, but the UA did not respond. At 29 seconds, the UA breached the geofence but later returned to the operational area. At 45 seconds, it was back within the geofence. At 49 seconds, OPT1 activated Pause Mission mode via the C2 UI, but the UA did not respond. At 63 seconds, OPT1 activated RTH mode, but it had no effect. UAP then switched the FCC from GUIDED to LOITER mode again, but the UA still did not hover. At 68 seconds, UAP activated Return to Launch (RTL) mode using the RC touchscreen. The UA flew towards the geofence boundary. At 71 seconds, the UA breached the geofence again, triggering the FCC's Failsafe Function RTL mode, but the UA flew further away. OPT1 then activated Stop Mission mode via the C2 UI.
At 85 seconds after take-off, while the FCC was in RTL mode, the UA flew towards and hit a residential building about 200m from the flight test area. It then dropped to the ground, landing approximately 1m from a person, and a fire ensued. There were no injuries.