After studying the details of the Zanthus 1968 case and the 1954 BOAC case, I was pleasantly surprised to come across a local 1954 newspaper article, involving another aircraft, which seems to me, suggestive of a possible mirage explanation.
Plane crew sees sky object.
The article appeared in The Advertiser (Adelaide, South Australia) dated Monday 11 January 1954, on page 1. The headline was "Plane crew sees sky object." The text reads:
"The crew of an ANA airliner reported last night having seen what appeared to be a strange object in the sky about 15 miles north of Morgan.
Captain W Booth, pilot of a DC3 which left Broken Hill for Adelaide at 6.25pm, said the object appeared on and off for about six minutes.
His co-pilot, First Officer Furness said the object seemed to move back and forth across their line of flight as though circling, but they could not catch up with it.
Both the men said the object must have been an optical illusion but could not explain how it occurred.
Capt. Booth said he probably would not have noticed the object at all had he not been watching out for a north-bound plane which was due to pass at 7.40pm.
At exactly that time he saw an object which he first thought was the other aircraft, but as it appeared to manoeuvre he thought it might be an RAAF plane.
The Sun had just set and the object which was practically dead ahead of the DC3 appeared to move quite fast from side to side and slightly from east to west.
Capt. Booth then learned from the Parafield control room that there were no other aircraft in the area and assumed that the sight was caused by refraction rays from the Sun.
After about six minutes it became too dark to see the object.
Capt. Booth said he had been flying for 14 years but had never seen a similar sight before.
First officer Furness said the object remained in view for about 10 minutes. It appeared to be circling slowly and resembled the silhouette of an aircraft at a distance of 40-50 miles.
"We sighted it at about 7.40pm 15 miles north of Morgan when we were flying at 8000 ft," he said.
:At first I thought it was another aircraft and wondered that it was flying at the same altitude as we were.
"We spoke to Parafield and were told that the nearest aircraft was a DC4 at Tailem Bend.
"I thought that it was an eagle flying unusually high, but we didn't seem to get any closer to it.
"It disappeared several times in the haze and cloud layer while it was circling."
First officer Furness said he felt the object must have been an optical illusion of some sort but he could not explain how it might have occurred."
1. Interestingly, as with Zanthus, the Morgan observation was from an aircraft flying at 8000 feet altitude.
2. As with Zanthus, a check revealed there were no other aircraft in the area at the time.
3. As with Zanthus, the Sun had just set. A check with an astronomical software program confirmed this.
4. As with Zanthus, the object appeared to be at the same altitude as the aircraft,