Sort: Trending
Part 2/9:
Toronto Pearson consists of five runways, interconnected through taxiways and aprons. The airport has parallel runways: 6L and 6R, 24L and 24R on the southern side; 15L and 15R, and 33L and 33R in the center; and a single runway 05/23 on the northern end. The incident in question occurred on runway 06L, while runway 05 was also active, which played a significant role in the unfolding events.
The Air Traffic Control Setup
Part 8/9:
The investigation concluded that a combination of optimized ATC workflows, reliance on pilot-applied visual separation, and the simultaneous transmission of critical communications led to a breakdown in situational awareness for all involved. Importantly, the RIMCAST system failed to warn the controller of the potential conflict because both aircraft were incorrectly perceived as airborne.
This incident exemplified the delicate balance of human factors, technological systems, and procedural adherence in aviation safety. Human intervention saved the day, highlighting both the need for rigorous monitoring systems and the unpredictable nature of concurrent communications during critical phases of flight.
Part 1/9:
Understanding the Bizarre Incident of Dual Takeoff at Toronto Pearson International Airport
When we think about aviation safety, it’s easy to assume that meticulous systems are in place to prevent accidents. However, sometimes it takes a bizarre incident to bring the vulnerabilities of these safety measures to light. On March 7, 2020, at 9:48 AM EST, a unique situation occurred at Toronto Pearson International Airport that starkly highlighted weaknesses in air traffic control protocols.
The Airport Layout
Part 3/9:
The air traffic control (ATC) tower is centrally located, which gives controllers a good visual on various parts of the airport, although some areas pose visibility challenges. There are nine workstations in the control tower, and during this incident, only four were occupied. The north tower controller managed not just runway 06L but also the other runways, indicating a heavy workload for the controller. He was in a combined position, meaning he was responsible for both north and south runway operations, which limited his ability to monitor all aircraft effectively.
The Technology in Play
Part 4/9:
Controllers have access to several tools designed to enhance situational awareness and prevent conflicts. One such tool is RIMCAST, which stands for Runway Incursion Monitoring and Conflict Alert System. RIMCAST utilizes ground radar and ADS-B (Automatic Dependent Surveillance–Broadcast) transponder data to monitor the status of aircraft on the runway. The system issues warnings in two stages based on proximity and speed, but here lies the crux of the issue—both warnings had limitations that played a critical role in this incident.
The Calm Before the Storm
Part 5/9:
On the day of the incident, the weather was clear with good visibility, allowing the controller to employ pilot-applied visual separation rules when managing departures. This method allows pilots to maintain visual separation between departing aircraft, which may increase operational efficiency. However, this strategy necessitates that the controller not clear a subsequent aircraft for takeoff until the preceding aircraft is airborne—a nuance that becomes critical to the narrative.
At 9:48 AM, an Air Canada Embraer 190 was cleared for takeoff from runway 06L. As the aircraft accelerated, it sent an ADS-B signal indicating it was airborne at 50 knots—considerably below the more common threshold of 100 knots to declare an aircraft airborne.
The Sequence of Events
Part 6/9:
As the Embraer began to take off, a second Air Canada aircraft, a Boeing 777 configured to take off soon after the Embraer, was simultaneously cleared to enter the runway and line up. Miscommunication ensued; the controller believed that the Embraer was about to leave the runway, while the crew of the 777 initiated their own takeoff roll, unaware of the complications developing ahead.
Things took a dramatic turn for the Embraer when the crew experienced a bird strike at 139 knots, prompting an immediate rejected takeoff. Unfortunately, while the first officer onboard the Embraer communicated this decision to ATC, their radio transmission was masked by the simultaneous readback of the cleared takeoff for the 777 behind them.
The Near-Collision
Part 7/9:
With the Embraer decelerating but still showing ’airborne’ status on RIMCAST, the Boeing 777 accelerated beyond 100 knots, also being classified as airborne. The controller turned their attention to other traffic, unaware that two aircraft were now on the runway at the same time, each with serious implications.
As the Boeing 777 reached a critical speed, its crew noticed, with alarm, that the Embraer was slowing down ahead of them. Realizing the potential collision, they initiated their own rejected takeoff. With about 5,000 feet separating the two planes, this decision effectively averted a serious incident.
Investigation and Summary
Part 9/9:
In the end, while the Boeing 777 and Embraer 190 both landed safely, this incident served as a stark reminder of the complexities and challenges faced in air traffic control, urging the industry to continue enhancing safety protocols to prevent future occurrences.