ATSB Report: Brisbane Air Traffic Controller Found Asleep on Night Shift

A Brisbane air traffic controller who was found asleep at their workstation had worked multiple consecutive night shifts, an ATSB report reveals.

An air traffic controller at Brisbane Centre was discovered asleep during their shift, prompting an ATSB investigation. The subsequent report reveals that sleep debt from consecutive night shifts was a contributing factor to the incident.

Cairns TCU Incident

On December 9, 2022, around 5:15 am, the incoming air traffic controller found their colleague asleep across two chairs, covered by a blanket. This occurred in the Cairns Terminal Control Unit within Airservices Australia’s Brisbane Air Traffic Services Centre.

Brisbane Centre is a major air traffic control centre, operated 24 hours a day by Airservices Australia at Brisbane Airport. The operations room was divided into aisles, each with 2 rows of consoles.

Each aisle was supervised by a manager working from a desk in the middle of the aisle (photo below), but during the night shift, there was no aisle manager on duty. A system supervisor was available for indirect supervision, and they were usually located at the front desk of the centre.

Investigation Findings

The investigation identified several factors leading to the controller’s unintended slumber:

1. Time of day

2. Extremely low workload in their sector

3. Multiple consecutive night shifts

4. Increased sleep risk due to lying down and inactivity

5. Lack of mental alertness maintenance

Due to a number of factors, the Cairns terminal control unit approach controller fell asleep while at their workstation.

These factors included the time of day (about 0500), very low workload, a roster pattern with multiple consecutive night shifts and the controller engaging in practices that increased the risk of falling asleep.

The controller had been working multiple night shifts with reduced extended rest periods, which likely reduced their ability to obtain restorative sleep. This increased the likelihood of experiencing sleepiness and sleep onset while on duty.

ATSB Chief Commissioner Angus Mitchell noted, “The controller had been working multiple night shifts with reduced rest periods, likely hindering restorative sleep.”

ATC Situation at Time of Incident

At the time of the incident, no air traffic was present in the Cairns TCU airspace, which was typical for that hour. No flights were scheduled until after the controller’s shift ended.

However, if awakened by a radio call, the controller might have experienced ‘sleep inertia’, potentially causing delayed communications or incorrect instructions. This could have impacted their ability to manage unexpected airspace infringements.

Mitchell emphasized, “While no negative consequences resulted, this incident highlights areas for improvement in work scheduling and fatigue risk management.”

The investigation also uncovered issues with Airservices Australia’s broader fatigue management approach. Mitchell explained, “An underlying resource shortage led to over-reliance on tactical roster changes. This prevented effective strategic management of cumulative fatigue.”

Airservices Remedial Actions

In response, Airservices has increased its air traffic controller numbers, particularly in the North Queensland group. The investigation found that Airservices’ fatigue assessment and control tool (FACT) could identify situational fatigue factors. However, its effectiveness was limited as supervisors weren’t recognizing low workload as a fatigue hazard.

Airservices has since developed additional guidance and training on fatigue risk assessment, including how to treat low traffic situations as high risk.

Furthermore, the Civil Aviation Safety Authority has introduced new air traffic service fatigue risk management system requirements. Airservices is collaborating with CASA to evaluate its existing system against these new standards.

Mitchell concluded, “Fatigue remains a significant concern for safe transport across the sector. We urge operators to thoroughly investigate fatigue events to address deficiencies in work scheduling, fatigue risk management processes, and risk controls.”