Aviation safety investigations & reports

Boeing Co 737-376, VH-TAZ

Investigation number:
Status: Completed
Investigation completed


A Lockheed C-130J Hercules (Hercules) had conducted a practice Instrument Landing System (ILS) approach to runway 35 at Canberra followed by a touch and go landing and departure to the northwest. A Boeing 737-376 (B737) was simultaneously radar vectored for an instrument approach to runway 17. Both aircraft intended to use the same runway surface but in opposite directions. The Canberra Approach East (CBE) controller became concerned that the separation standard of either 3 NM laterally or 1,000 ft vertically would not be maintained between the aircraft and issued turn instructions to both crews. While complying with the instructions the two aircraft passed with approximately 2 NM and 100 ft separation. There was an infringement of separation standards.

The Hercules crew had requested an ILS approach to runway 35 at Canberra for instrument flight rules (IFR) flying training purposes. An ILS is a precision instrument approach that provides centreline and glideslope guidance to the pilot, aligned to the landing runway and is primarily used during periods of low cloud and/or poor visibility. Runway 35 was the only runway serviced by an ILS approach at Canberra. The En Route Supplement Australia (ERSA) required crews planning instrument training at Canberra to contact Canberra air traffic control to book an approach time slot for air traffic control traffic management purposes. The service provider reported that the Hercules was running late and had missed its booked slot.

The CBE controller planned to sequence the Hercules between the second of two aircraft taxiing for a departure from runway 17 and the B737, which was the first of a number of arrivals for that runway. The CBE controller was aware that the Hercules' practice ILS approach might be delayed by up to 45 minutes if he was unable to sequence that aircraft ahead of the B737. The CBE controller stated that he felt some pressure to provide a good service to the Hercules crew.

On first contact with the CBE controller the B737 crew was told to expect a Very High Frequency Omni-Directional Radio Range/Distance Measuring Equipment (VOR/DME) approach to runway 17. At various times thereafter, the crew was assigned radar vectors and a speed restriction of 270 knots indicated airspeed to position the B737 behind the Hercules and provide sufficient spacing to maintain the required separation standard. The CBE controller had asked the crew of the Hercules to maintain their best speed once established on the final approach track. That was a request only and the crew of the Hercules was under no obligation to comply. From that point, the Hercules was capable of maintaining an indicated airspeed between 10 to 20 kts faster than that which it would routinely maintain. The crew of the Hercules could not recall whether they had complied with the request.

The CBE controller was concerned about the application of separation between the B737 and the Hercules after the Hercules had completed its touch and go landing. The Letter of Agreement between the Canberra Tower and Canberra Approach Control stated that the approach controller was responsible for separation assurance during reciprocal runway operations unless it was assigned to the ADC "by mutual agreement". The CBE controller advised that his contingency plan was to instruct the B737 crew to terminate the approach if it became apparent that separation between the two aircraft may be infringed.

The CBE controller reported that he had based the traffic management plan on his expectation that the Hercules would be operated at a higher speed along the final approach path. The CBE controller also reported that the Hercules had commenced its turn later than he had expected following the touch and go landing. He could not see the Hercules on radar following the touch and go landing and was unsure of the position of that aircraft in relation to the B737. The CBE controller asked the ADC to confirm when the Hercules had commenced the turn and was visually clear of the inbound path of the B737. The ADC was unable to provide visual separation between the B737 and the Hercules before radar and vertical separation were infringed.

The CBE controller reported that his workload was very high at the time of the occurrence. He did not provide either crew with a safety alert in respect of the other aircraft, as required by MATS, despite the distance between the two aircraft being less than that prescribed by the applicable separation standards.

Both aircraft were equipped with a traffic alert and collision avoidance system (TCAS). The crew of the Hercules did not receive either a traffic advisory (TA) or a resolution advisory (RA) on the TCAS. The crew of the B737 did not report receiving a TA or a RA either during, or after, the occurrence.


The CBE controller had developed a plan to provide the Hercules crew with a practice ILS. He unsuccessfully applied speed control and radar vectors to both the Hercules crew and the B737 crew to execute the plan and to achieve the required separation. As a contingency, the CBE controller planned to terminate the approach of the B737 if that became necessary to maintain required separation standards. However, the plan did not provide any separation assurance between the Hercules and the B737.

The CBE controller did not apply a separation standard between the Hercules and the B737 from the time the Hercules descended below radar coverage in the Canberra circuit area until the ADC accepted responsibility for separation following the touch and go landing. A procedural separation standard between the Hercules and the B737 should have been applied while the Hercules was outside radar coverage and while the ADC could not provide visual separation.

Safety Action

Local safety action

On 3 Feb 2000, Airservices Australia undertook to investigate methods to enhance controller awareness and application of the concept of separation assurance through, among other initiatives, the production and dissemination of information and a review of MATS. As at 24 May 2002, Airservices Australia had;

  1. included separation assurance as a refresher training module,
  2. highlighted occurrences in which a lack of separation assurance may have been a contributing factor, and
  3. described separation assurance, in MATS, in terms of conflict avoidance rather than conflict resolution.

ATSB safety action

Airservices Australia advised the ATSB on 21 April 2002 that it was reviewing all aspects of separation assurance matters, which will include a definition of separation assurance. On 26 July 2002, further correspondence from Airservices indicated that a definition of separation assurrance would be included in the next amendment of MATS. The ATSB will continue to monitor these separation assurrance matters until the amendment is promulgated.

General details
Date: 24 July 2001   Investigation status: Completed  
Time: 1815 hours EST    
Location   (show map): Canberra, Aero.    
State: Australian Capital Territory   Occurrence type: Loss of separation  
Release date: 12 August 2002   Occurrence category: Incident  
Report status: Final   Highest injury level: None  

Aircraft 1 details

Aircraft 1 details
Aircraft manufacturer The Boeing Company  
Aircraft model 737  
Aircraft registration VH-TAZ  
Serial number 23491  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Melbourne, Vic.  
Destination Canberra, ACT  

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer Lockheed Georgia Co  
Aircraft model C-130J  
Damage to aircraft Nil  
Departure point Richmond, NSW  
Destination Richmond, NSW  
Last update 13 May 2014