On 16 November 2014, a Robinson R44 helicopter, registered VH-YDK (YDK), was approaching Jandakot Airport on a charter flight from Rottnest Island, Western Australia, with a pilot and three passengers on board. At about 1348 Western Standard Time, the pilot of YDK reported downwind for runway 24 on the Jandakot Tower frequency.
At about the same time, the pilot of a Bell 412 helicopter, registered VH-EWA (EWA), prepared to conduct a rescue flight to Bunbury, Western Australia, with a crewman and paramedic on board. As YDK turned onto final, at about 400 ft above ground level (AGL), the pilot of YDK sighted EWA outside its hangar and elected to continue the approach.
At about 1350, the pilot of EWA requested to taxi to the compass swing bay on the Ground frequency. As the pilot commenced taxiing, the crewman sighted YDK at about 150 ft AGL and on an approach towards EWA. He directed the pilot of EWA to go forward.
At about 1350, the pilot of YDK broadcast on the Tower frequency: ‘YDK just out your left hand window’. The pilot of EWA was monitoring the Ground frequency and did not hear that call. YDK then descended and passed behind EWA towards a landing on the middle of the grassed area.
The pilot of EWA continued to taxi towards the compass swing bay, and when approaching the bay, first sighted YDK which was then passing behind EWA and about 30 m away.
The environment and procedures in the helicopter precinct at Jandakot require that pilots make the mandatory radio calls, maintain a good lookout and taxi, depart and approach the area by the most predictable routes to assist others in sighting them.