On the evening of 30 November 1961, Ansett-ANA Flight 325, a service from Sydney to Canberra, Australia, operated by a Vickers Viscount 720, broke up in mid-air and crashed shortly after takeoff, when it encountered a severe thunderstorm.

On board were the pilot, Stan Lindsay; co-pilot, Ben Costello; two air hostesses, Aileen Keldie[6] and Elizabeth Hardy; and eleven passengers.

Accident Investigator Frank Yeend wrote "The weather was so bad that this aircraft crashed in the middle of a major city without anybody having seen it or heard anything that would give cause to alarm.

"[1] When it became clear Flight 325 was not responding to radio calls and the aircraft could not be seen on the radar screen in the control tower the Alert Phase of search and rescue procedures was initiated.

In the hours after loss of contact with Flight 325 no report was received of an aircraft accident so there was general foreboding that it had crashed into the Tasman Sea.

At the south of the Bay the outer section of the right wing, still showing registration VH-TVC, was found protruding above the surface of shallow water near Kurnell.

[Note 4][13] Later in the day police and navy divers investigated a large fuel slick in the centre of Botany Bay and discovered the scattered wreckage of VH-TVC in 25 feet (7.6 m) of water, 1.6 miles (2.6 km) north of the outer section of the right wing.

[Note 5][15] The Royal Australian Navy sent a team of clearance divers and HMAS Kimbla, a boom defence vessel, to Botany Bay and brought the main wreckage of VH-TVC to the surface.

[14][16] Numerous small items, including many from the number 4 engine nacelle, were found on Kurnell peninsula, south of the outer section of the right wing.

[Note 7][23] [dead link‍] As pieces of wreckage from VH-TVC were progressively recovered from Botany Bay they were laid out in a hangar at Sydney airport to allow investigators to search for the cause of the accident.

[25] Engineers assisting the accident investigation calculated that for the wing spar to fail in the way it did in VH-TVC would require the aircraft to be flying faster than its maximum speed of 260 knots (480 km/h) and, while being subjected to a severe recovery manoeuvre by the crew, to encounter a very strong gust, possibly as much as 100 feet per second (30 m/s).

By making assumptions about the likely terminal velocities of key pieces of wreckage, accident investigators were able to determine the approximate location, height and speed of the aircraft at the time it broke up.

They believed the outer section of the right wing was torn away when the aircraft was south of its intended flight path, heading in a northerly direction, and at a height between 3,500 and 5,500 feet (1,070 and 1,680 m).

While flying north, possibly in an attempt to escape the thunderstorm, the crew encountered continuing strong turbulence that caused control to be lost again.

The circumstances and available evidence carry a strong implication that the in-flight structural failure was preceded by a loss of control with a consequential increase in speed to at least 260 knots.

The most probable explanation for the loss of control is that the aircraft entered an area of unexpected turbulence of such severity as to deprive the pilots of full recovery.