A Qantas flight heading to South America turns back to Melbourne after almost five hours into the journey, according to reports. The aircraft makes a sudden U-turn over the Pacific with nearly 200 passengers on board, prompting the return trip. The outlets describe the incident occurring mid-flight, with the plane reversing course rather than continuing onward to its destination. No additional details about the cause of the U-turn are included in the provided accounts. The reports focus on the timing of the turnaround and the number of passengers aboard at the time the decision is made to return to Melbourne. Overall, both sources present the same core facts: the route was toward South America, the flight changes course over the Pacific after close to five hours, and the passenger count was just under 200. Further information on any technical issue, operational reason, or passenger experience during the return is not specified in the supplied text.