Loss of separation involving a The Boeing Company 727-277, VH-ANF and The Boeing Company 737-377, VH-CZI, 45km N Maroochydore, VOR, QLD on 12 June 1996

A Boeing 727 and a Boeing 737 were both on descent to Brisbane from the north. The B727 was ahead of the B737 and was instructed to reduce speed to 230 knots for sequencing. As the speed reduction took effect the following B737 closed rapidly, and the situation was not observed until both aircraft were at flight level 255 and 3.1 nm. Minimum separation is 5 nm. The B737 was turned onto a heading of 180 degrees for avoidance, and there was no further closure. The traffic situation at the time was light, following a relatively busy period. There was no underlying reason for the controllers failure to maintain the required separation standard. There appears to have been a lapse in concentration following a period of heavy traffic.