The crew of a BAe 146, VH-NJU, did not intercept the localiser while conducting the Brisbane runway 19 Jacobs Well 5 standard arrival route. The resultant track of the aircraft placed it in conflict with an Airbus A320, VH-HYC, which was tracking via the Brisbane runway 19 SMOKA 4 standard arrival route. Vertical separation was reduced to approximately 500 ft and horizontal separation was reduced to 2 NM.
Examination of air traffic control radar plots and the flight path derived from NJU's flight data recorder (FDR) revealed that it had passed through the localiser while maintaining a heading of approximately 280 degrees. Approximately 0.5 NM before NJU passed through the localiser, the air traffic controller asked the crew of NJU to confirm that they were turning onto the localiser. The crew confirmed to the controller that they were turning onto the localiser; however, NJU maintained the original track until it was approximately 1.5 NM beyond the localiser centreline. The FDR revealed that a localiser deviation of 5 dots would have been displayed on the flight navigation instruments at that point. The aircraft then commenced a left turn onto a heading of approximately 170 degrees. The new heading was maintained for approximately 25 seconds, at which stage the controller directed the crew to continue the left turn onto heading 140 degrees to intercept the localiser.
The pilot in command of NJU reported that the aircraft experienced tailwinds and was flying through rain during the intermediate part of the approach. The co-pilot was the handling pilot for the sector, and the pilot in command's attention was diverted to the airborne weather radar, which was indicating returns in the vicinity of the aircraft's flight path during the intermediate approach. The aircraft overshot the intercept of the localiser when the co-pilot did not initiate the inbound turn in a timely manner. The overshoot resulted in a full-scale deflection of the course deviation bar on the navigation instruments. After the co-pilot initiated a left turn onto a southerly heading in an attempt to re-intercept the localiser, the pilot in command realised that the heading would not result in the aircraft intercepting the localiser and informed the co-pilot that the revised heading was inadequate. At about the same time, the controller instructed the crew of NJU to turn further left onto a heading of 140 degrees to expedite the intercept.
The pilot in command of NJU reported that he noticed the lights of HYC on the other side of the localiser prior to NJU's overshoot of the localiser. The pilot in command of HYC reported that they had been cleared for a runway 19 SMOKA 4 STAR and that after passing DAYBO, they had proceeded on a heading of 093 degrees to WISPA in accordance with the standard arrival route. As HYC was descending from 7,000 ft to 3,000 ft, the crew observed a traffic alert and collision avoidance system (TCAS) target on the cockpit navigation displays and the controller confirmed that they were to follow NJU. Shortly after, the controller advised the crew of HYC to turn left 30 degrees due to NJU overshooting the localiser, and as the crew of HYC commenced the left turn they received a TCAS alert.
In accordance with the Aeronautical Information Publication Enroute Section 1.1-2 paragraph 3.8, crews may request vectors or position advice from air traffic control to assist them in complying with standard arrival routes, particularly in tailwind conditions. The investigation was unable to determine why the crew of NJU did not request radar vectors to assist in the timely establishment of the aircraft onto the localiser in the weather conditions that were encountered at the time. The investigation identified crew coordination and flight management deficiencies, which included the pilot in command's reduced awareness and monitoring of the co-pilot's handling of the aircraft and its flight path.