I contacted ATSB today to ask if there was any record of the VH-BAT dive incident. The lady was most helpful and said as the incident was in 1960 any record would be held at the National Archives. I have submitted the request for information to the NA.
Having flown Viscounts in the RAAF in 1965 I was curious at what would have caused such an unusual manoeuvre in the first place. Perhaps over-controlling during recovery from an unusual attitude? Easy to happen. There were no Viscount full flight simulators in those days so no opportunity to practice realistic unusual attitudes. Was it a CB encounter gone wrong? Wake turbulence? Tornado in certain types of cloud formation? The quoted report from the Viscount history website was written up by someone who had interviewed both pilots.
Re the Ansett Viscount that broke up in mid-air over Botany Bay in November 1961.
By coincidence I talked to a friend of mine today who was a young commercial pilot on duty at the company operations office at the airport on the day of the accident. He said there was a very severe storm with heavy rain over the airport an hour before the departure. He was talking to the pilots of the Viscount during flight planning and were all looking out of the window at the thunder and lightning low cloud and blinding rain. After a while the captain said something like "Well we may as well give it a go" and walked out of the office. That was the last he saw of them. Parts of the aircraft were later found on the actual aerodrome indicating it had broken up almost over the 'drome even though major parts fell into Botany Bay.
At the subsequent Board of Inquiry evidence was presented that at
the time of departure of VH-TVC there was a flash of lightning and loud thunder which prompted a remark by someone in the Tower to the effect that it sounded as if an aircraft had blown up.
Makes you wonder in hindsight why the captain chose to depart in such severe weather knowing the aircraft was not fitted with weather radar.
Two of the points made in the summary by the Board of Inquiry into the accident were:
26) At the time of the failure of the starboard outer wing the aircraft was travelling at a speed in excess of 260 knots and at an appreciably higher speed when it struck the water.
(27) It is probable that action by the pilot to recover control of the aircraft during its rapid descent imposed a manoeuvre load on the aircraft which together with its speed and turbulence encountered, produced forces in the aircraft structure greater than it was designed to bear and which failed the starboard outer wing.
Remarkable similarity to the Braniff BAC One Eleven mid-air break-up in clear air between two huge storm cells over Nebraska USA. See:
https://en.wikipedia.org/wiki/Braniff_Flight_250
Talked to a Met officer about the Viscount break up over Sydney and he said certain types of super storms can generate violent vortices inside these clouds or in the clear air between them and these clouds have been known to exist in Australia.