A QANTAS Airbus A330 flying into Melbourne aborted a landing last week after its ground proximity warning system activated. The Australian Transport Safety Bureau is investigating the March 8 go-around and the warning, which is usually activated if the aircraft is too low. It is understood to have been sparked in this case by the aircraft's rate of descent. "The crew received an aircraft system-generated ground proximity warning and conducted a missed approach in accordance with the operator's procedures," the bureau said. A Qantas spokesman said last night the airline was investigating the cockpit warning.