At about 1000 hours local time on 19 June 1985, Garuda Boeing 747 aircraft PK-GSB, operating as Garuda Flight 898, was being radar vectored by Melbourne Air Traffic Control (ATC) for a landing on runway 34 at Tullamarine Airport. Shortly after the pilot acknowledged an instruction to call Melbourne Tower the aircraft was seen to turn and descend as though making an approach to runway 35 at Essendon Airport. The Melbourne Tower controller instructed the aircraft to climb to 3000 feet above mean sea level (amsl), and a few seconds later the aircraft was seen to be established in this climb. After further radar vectors were given,an uneventful landing was carried out at Melbourne. It was subsequently determined that the aircraft had descended to a minimum height of approximately 350 feet above the level of Essendon Airport, and was about 1.5 kilometres from the runway threshold before the climb was commenced.