What happened
Following a series of separation losses between aircraft at Lester B. Pearson International Airport in late 1988, the Canadian Aviation Safety Board (CASB) launched a special investigation into the nation's air traffic control (ATC) environment. The inquiry sought to identify safety deficiencies within the Air Traffic Services (ATS) system that could lead to midair collisions or ground incidents. The investigation reviewed a database of 710 occurrences between 1985 and 1988, specifically focusing on incidents involving aircraft weighing more than 5,700 kilograms operating under instrument flight rules in high-level airspace and the Toronto and Vancouver terminal control areas.
The investigation
The CASB conducted a detailed review of 217 selected incidents and performed over 80 interviews with air traffic controllers, managers, and various aviation industry representatives. The scope of the study examined the safety of the ATS system without attempting to forecast long-term technological needs or address specific airport capacity constraints. Analysts evaluated the impact of equipment, staffing, training, and human performance factors on the ability of controllers to maintain safe aircraft separation.
Findings
While the investigation noted that the ATS system handles thousands of daily flights with a low overall error rate, it identified several critical vulnerabilities. The most significant finding was a severe shortage of qualified air traffic controllers to meet rising operational demands. This shortage has forced supervisors to work operational positions, compromising oversight, and has led to a heavy reliance on voluntary overtime.
Other identified contributing factors included:
- High rates of attrition and long qualification periods within the training system.
- Human performance errors, including lapses in attention and judgment, which accounted for nearly 60% of analyzed files.
- Breakdowns in information transfer, particularly during oral communications, contributing to half of all separation losses.
- Operational pressures that led some controllers to bypass standard procedures to manage high traffic volumes.
- Inconsistencies in how incidents are investigated between the CASB and Transport Canada.
Safety action
The investigation resulted in 48 Aviation Safety Recommendations aimed at improving the safety of Canadian air traffic services. These recommendations address themes such as equipment, training, supervision, and management. The report noted that several large-scale initiatives, including the Radar Modernization Project and the Canadian Automated Air Traffic System, were already underway to address technical shortcomings.