Loss of separation involving a Boeing 747, 9M-MHJ and Boeing 767-238, VH-EAK, Melbourne Aerodrome, Victoria, on 13 November 1997

The crew of an international Boeing 747 departing runway 16 had been cleared for a KEPPA 1 Standard Instrument Departure. Departure instructions had been issued by Departures North for the aircraft to initially maintain 3,000 ft due to overflying traffic. The B747 was rolling when the tower controller called Departures North to obtain departure instructions for a Boeing 767, that had been cleared for a DOSEL 6 Standard Instrument Departure from runway 27. The Departures North controller indicated he would call back shortly with departure instructions in respect of the B767.

The departures controller observed the B747 airborne and cleared the aircraft to continue its climb, having established that separation existed with the overflying traffic. At this stage the departures controller called the tower controller and issued departure instructions for the B767 to maintain 3,000 ft. This would allow the B767 to pass under the path of the departing B747.

The departures controller subsequently observed the B767 to be airborne, with the B747 still south-west of the aerodrome, in a left turn climbing slowly through 2,800 ft. As the controller considered the B747's rate of climb insufficient to preserve vertical separation between the two aircraft, the departures controller turned the B747 onto a westerly heading and passed traffic information to the crew in respect of the B767.

Horizontal separation between the two aircraft reduced below the 3 NM standard before vertical separation standards were established. The two aircraft were further processed without incident.