On 6 April 1966, at about 11:00 AM in Clayton South, Melbourne, students and teachers at Westall High School reported seeing one or more disc- or saucer-shaped objects, silvery or grey in color, sometimes described with a slight purple hue. Witnesses say the object hovered above the school oval, descended behind trees into a nearby paddock known as The Grange, and after a short time rose sharply and vanished toward the northwest. Over one hundred people—mainly schoolchildren and staff—took part in the events, which unfolded in broad daylight in a suburban school environment. The incident is widely regarded as one of Australia’s most famous mass UFO sightings.

Descriptions from the day vary in detail. Some witnesses said the craft was twice the size of a family car, others saw additional smaller objects or aircraft, but no consensus on every detail. Teachers such as Andrew Greenwood reportedly saw a silver-green disc. Some students claimed flattening or burn-marks in grasses at the landing zone, circular depressions, or “pressed down” turf near The Grange.

Contemporary reporting included local newspapers like The Dandenong Journal, which published stories in mid-April 1966. The Age newspaper mentioned the incident a day after (7 April), proposing a weather balloon might explain what was seen, based on a balloon released at Laverton earlier that morning and carried by westerly winds. Military or Air Force records show no obvious corroboration of aircraft sorties or official craft operations over the school at that time. Long after 1966, researchers examined documents indicating that balloon tests under the HIBAL program (used for monitoring radiation from British nuclear tests) may have involved launches from Mildura which drifted off course, potentially ending near Clayton South.

According to some of these accounts, the appearance of the balloon—white, silvery, with trailing gas hoses or tubes—bears resemblance to how witnesses described the UFO. Compensation in narratives through decades also introduced more unusual claims, including suggestions that witnesses were pressured by “men in suits” to remain silent. Skeptical analyses focus on how memory and community storytelling may have shaped how the event has been remembered. Years after, interviews with witnesses show both strong agreement on core details (shape, color, roughly where The Grange was, timing during morning recess) and divergence in other specifics (how many objects, precise size, whether the object landed).

The weather-balloon hypothesis remains one of the main non-paranormal explanations. Some argue that over time, embellishments or conflations have joined the original memory. Despite the doubts and debates, Westall’s enduring significance is rooted in how public, early in the day, and collectively witnessed the event was. It did not happen in isolation—it took place amid regular school life, involved teachers and students with little incentive to fabricate an event, and was reported immediately in local media.

It has become a reference point in Australian discussions of what counts as reliable mass witness testimony. The traces of grass, the multiple interviews over decades, the alternate hypotheses offered—all contribute to why it remains unresolved in many eyes.