It is always interesting to hear about a possible mundane explanation for what has always been regarded as a classic UFO sighting.
An Australian classic is the 22 August 1968 Zanthus, Western Australia case. (Click here for a catalogue of Australian observations of UFOs from aircraft crews and passengers.) Here, two pilots were flying an aircraft from Adelaide to Perth on a charter flight. They noted an unusual sight in the sky. It appeared to be on the same level as their aircraft and to them was a "formation of aircraft." However, a query to Kalgoorlie DCA revealed there was no other traffic in the area. The main UFO split in to two and there were smaller ones which moved to left and right of the main object at the same level as the aircraft. The two halves of the main object joined and split. Finally, the entire thing diminished in size and was gone.
The case has remained a mystery until now.
The possible explanation for the Zanthus case as a mirage,comes from a detailed re-examination of the 29 Jan 1954 classic Labrador BOAC event where a very similar observation was made to the Zanthus case.
Click here for a link to the re-examination of the Labrador event.
Take some time to have a good read at this excellent piece of detective work, and see what you think about the cause of the Zanthus event. I'd love to hear your views.
PS The Labrador research also lists another Australian case, that of 27 Jan 1959 at Green Head, Western Australia.