Apellix B1 Washing Drone accident near Orlando, Florida, February 20, 2024

The NTSB's narrative final · quoted from the NTSB record

The remote pilot in command (RPIC) reported that shortly after takeoff, the small unmanned aircraft system (sUAS) was repositioning when it started to move erratically and would not respond to given commands. The RPIC attempted to disarm the sUAS by moving the control sticks down and inward, as he was instructed during his abbreviated training; however, the sUAS did not respond to the command and continued to operate erratically. The RPIC decided to disarm the sUAS by manually grabbing the sUAS and unplugging the battery. While disarming the sUAS, the RPIC sustained serious injuries from the propeller blades. Following the accident, the operator sent the sUAS to the manufacturer for repair without authorization. As a result, the sUAS and the controller could not be examined by the NTSB after the accident. The manufacturer had recovered data from the sUAS’s flight controller after it was returned to them, and those data were forwarded to the NTSB and examined. The data showed that the sUAS remained connected to the control station during the flight and that the event log reported a compass/magnetometer error on multiple occasions. A failure in the magnetometer could result in a compass error, and the sUAS moving erratically. The data also showed that despite the RPIC’s report that he attempted to disarm the sUAS, the control sticks were never moved to the correct position to disarm the sUAS. A review of the manufacturer’s operator’s manual and user manual for the sUAS revealed that there were no instructions on how to disarm the sUAS in an emergency. Aerial imagery of the accident location showed the sUAS was operating on a hospital roof with a large rectangular structure that was consistent with a commercial air conditioning unit that could result in magnetic interference. Given this information, it is likely that the sUAS’s magnetometer failed shortly after takeoff and while in close proximity to the commercial air conditioning units, which resulted in the sUAS’s erratic movements.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.