Aviation authorities will review the flight path between Melbourne and Cairns after two passenger aircraft came too close and had to take evasive action.
The aircraft involved were a Qantas 737 bound for Melbourne on August 30, 2013 and a Tiger Airways A320 on the reverse leg to Cairns, both using a two-way route.
At 4.24pm an air traffic controller noted a "conflict alert" as the two jets came within 25km of each other at the same altitude over southwest NSW, an Australian Transport Safety Bureau report said.
Both flights were instructed to turn right and return to a safe separation distance.
"As a result of this occurrence, Airservices has advised the ATSB that they will review the Melbourne to Cairns air route with regard to creating one-way routes," the investigation report said.
No one was injured in the incident which the ATSB categorised as serious.