The Australian Transport Safety Bureau has concluded its investigation of an incident in late March, when an ‘unknown object, possibly an unmanned aerial vehicle’ found itself in the flight path of a De Havilland DHC-8 turboprop plane.
On March 19, the plane was approaching Perth Airport when the crew saw a ‘bright strobe light directly in front of the aircraft,’ at about 3,800 ft., in controlled airspace. The light was on an unknown object that was ‘cylindrical in shape and grey in colour.’ The ATSB could not confirm the details of the object, but the crew of the DHC-9 did not receive a traffic collision avoidance system alert prior to the incident, which suggests that the object was, in fact, relatively small.
‘The pilot took evasive action, turning towards the west to avoid a collision with the object,’ the ATSB reports. ‘The object passed about 20 meters horizontally and 100 feet vertically from the aircraft.’
The airspace below 3,500 ft. in the vicinity is military restricted airspace, but the Australian Defence Force told the ATSB that it was not operating UAVs at the time and was not aware of any other groups performing UAV operations in the area. Further ATSB investigation confirmed these facts, leading the regulator to speculate that the possible UAV was being used near the airport by a recreational operator.
The ATSB, which noted that the use of such UAVs ‘outside of the regulations’ could ‘pose a significant risk to aviation safety,’ deemed the near-miss a ‘Serious Incident’ in the report's occurrence category.