Australia's crash investigator has found that high workload, inexperience and fatigue in air-traffic controllers were contributing factors in two near misses involving planes operating from Perth Airport.
The Australian Transport Safety Bureau yesterday released reports on near misses over Ceduna and north of Karratha, which it has termed serious incidents.
On November 8, 2011, a near miss happened over Ceduna in South Australia between a Virgin Blue 737 flying from Perth to Brisbane and a Qantas 737 operating from Port Hedland to Melbourne.
The planes were on converging tracks at 39,000ft when the longitudinal separation standard of 37km was infringed.
In the other incident, on January 18 last year, there was a near miss north-west of Karratha between an Airbus A320, of Tiger Airways operating from Singapore to Perth and an Etihad Airways Airbus A340-600 flying from Sydney to Abu Dhabi.
It was estimated that the planes missed each other by two minutes.
Airservices has changed the configuration, training and rostering arrangements of controllers for the sectors involved. A new radar in northern WA has alleviated controller workload and enhanced surveillance.