A93C0208 - Risk of Collision Between Air Canada A320 211 Airbus C-FDRP and Canadian Airlines International A320 211 Airbus C-FLSS Thunder Bay, Ontario 40 nm NW 3 December 1993

Safety Action Taken

Since the occurrence, shift scheduling for the Winnipeg ACC has been revised. Controllers are now scheduled so that supervisors can conduct "standback" supervision from 0800 to 1630 local on weekdays.

Provision of Standback Supervision

The CASB's Report on a Special Investigation into Air Traffic Control Services in Canada (March 1990) found, inter alia, that supervisors had been working at control positions when many of the loss-of-separation incidents had occurred. The report recommended that operational restrictions be placed on supervisors performing in direct control positions to provide a more effective supervisory presence (CASB 90-28). In response, Transport Canada (TC) indicated acceptance of the recommendation and agreed to implement it with the proviso that, due to staff shortages, supervisors would be required to work control positions occasionally.

Since making that recommendation in 1990, the TSB has investigated eight occurrences2, including this one, in which the lack of standback supervision was a factor. In its final reports on two of these occurrences3, the Board expressed concern that supervisors were still working at direct control positions and were not available to provide standback supervision during busy traffic periods.

The Board recognizes the difference between the role of a supervisor to schedule the work and relief of controllers assigned to sectors under his responsibility and the requirement to maintain situational awareness of overall traffic levels and workloads at these sectors. When a supervisor is working at a control position, the operational supervision of controllers and the maintenance of an overall awareness of the evolving air traffic situation will suffer.

TC has developed new target staffing levels for controllers, partially as a result of the aforementioned recommendation for standback supervision. Reportedly, the TC Resource Alignment Process visited the Winnipeg Area Control Centre (ACC) in July 1993, and provided the ACC with adequate staffing numbers to reduce the need for supervisors to work control positions during the core hours of 0800 to 2400 local. However, as TC has acknowledged, due to financial and staffing constraints, full time direct supervision is not always possible. (As indicated in section 4.1 of this report, the shift schedule at Winnipeg has been revised to provide "standback" supervision from 0800 to 1630 hours local on weekdays.)

Supervisory presence to oversee operations is not in itself a guarantee against occurrences. However, in view of the frequency of serious loss-of-separation incidents in which lack of supervision continues to be a contributing factor, the Board recommends that:

The Department of Transport conduct risk assessments by ATC unit to confirm that currently available controller forces are optimally deployed. A94-27

Transport Canada Response:

Transport Canada Aviation (TCA) supports this recommendation. The Air Traffic Services Branch has already initiated a "Resource Utilization Assessment" of all Area Control Centres and major Control Towers. A risk assessment of the supervision and deployment of staff will also be completed.

Once the reviews are completed, a national comparison report will be prepared with recommendations to ensure that the best operating practices are identified and implemented at all units.

In addition to the above, longer term initiatives include the Instrument Flight Rules (IFR) Workload Measurement Project and the Scheduling Project. These projects involve the development and implementation of an automated system to determine the controller requirements during a given time frame at specific workstations, and an automated system for the optimum scheduling of staff to meet identified systems requirement.

Situational Awareness

A high degree of vigilance is essential for sustaining awareness of developments in dynamic situations. In this investigation, it was found that the controller did not effectively monitor the traffic, nor take timely action to resolve the conflict. The manner in which the controller planned, executed, and monitored the air traffic was not conducive to maintaining good situational awareness, particularly during periods of light traffic. Several studies of operational errors, including a study of operational irregularities in the Canadian air traffic system (Stager and Hameluck, 1990), identified that a failure to maintain adequate situational awareness was the likely cause of most errors.

In its Report on a Special Investigation into the Risk of Collision Involving Aircraft On or Near the Ground (August 1987), the CASB noted that vigilance is the key to collision avoidance. Yet, the methods for stimulating and maintaining the high levels of vigilance requisite for collision avoidance are not well understood. Therefore, it was recommended that the Department of Transport initiate a multi-disciplinary study on the most effective means for sustaining vigilance, particularly for controllers under periods of low activity rates (CASB 87-41). In the subsequent Report on a Special Investigation into Air Traffic Control Services in Canada (March 1990), the CASB noted that TC was only planning to take action to determine the methodology and personnel requirements to conduct an analysis of means of sustaining vigilance. It was then further recommended that the Department of Transport accelerate all technical initiatives with a potential for providing controllers with automated conflict prediction and alerting (CASB 90-36).

A traffic conflict warning system is being included in the Radar Modernization Project (RAMP), but it is not yet functional. However, automated systems still require high levels of operator vigilance to monitor the effective performance of the systems. The Board is concerned that the RAMP warning system may create a false sense of security, lessening the perceived need for continued high controller vigilance. Analysis of flight crew performance in highly automated cockpits has shown that inadequate monitoring of automated flight management systems has resulted in loss of situational awareness; in such cases, considerable time is required for the operator to get "back into the loop" and revert to backup procedures should the "system" fail. The aviation industry continues to grapple with the issue of sustained vigilance and maintenance of situational awareness in automated cockpits. The Board believes that a thorough understanding of the mechanics of sustaining vigilance in an automated ATC environment will also be critical for the maintenance of a safe air transportation system.

Controller inattention, lack of vigilance, or loss of situational awareness continue to be major factors in loss of separation occurrences. Therefore, the Board recommends that:

The Department of Transport sponsor research into methods for maintaining reliable controller vigilance in an increasingly automated ATC work environment. A94-28

Transport Canada Response:

Transport Canada Aviation (TCA) agrees with this recommendation and will conduct research on the most effective communication, focusing and distraction control techniques for air traffic controllers and implement relevant training programs. TCA has started doing research on other areas that impact on controller vigilance, e.g., workload and traffic levels, more effective scheduling tools, the effects of shift work and overtime on the health and performance of controllers. TCA has also implemented the following preventive and facilitative programs designed to optimize air traffic controllers health and performance: "Air Traffic Controller Chemical Critical Incident Stress Education and Peer Support Program", and the "Air Traffic Controller Occupational Health Program". Air traffic controller ab initio trainees at the Transport Canada training Institute (TCTI) are given a module called "Mental Control" which teaches trainees focusing, distraction control and visualization techniques to optimize their performance.

In the meantime, given that an operational overview by standback supervisors may not always be available, the Board believes that immediate measures must be taken to enhance the skill required by controllers for maintaining situational awareness.

Maintaining situational awareness is one of the key skills developed in crew resource management (CRM) programs. The Board understands that the concept of CRM training for flight crews is being adapted for controllers, and situational awareness training specific to air traffic control is being developed in other countries. Therefore, to assist controllers in their maintenance of situational awareness, the Board recommends that:

The Department of Transport provide training for Canadian controllers similar to CRM training for pilots. A94-29

Transport Canada Response:

Transport Canada Aviation (TCA) does not feel that the Crew Resource Management (CRM) training designed for pilots is applicable to the controllers. A decision making course similar to the Pilot Decision Making course is felt to be more relevant. This type of training will be researched and an appropriate training course developed.  Action has already been initiated to implement a system safety awareness program. A position for an Air Traffic Services (ATS) controller has been established within the Safety Programs Branch and an ATS Safety Newsletter was published recently. These Newsletters will be published on a regular basis.  Safety awareness training will also be pursued for introduction at TCTI. 


2 TSB occurrences A90P0347, A90H0008, A92H0003, A92H0028, A92H0035, A93O0203, A93A0118

3 TSB occurrences A90P0347 and A90H0008

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