Thinking Tools

Accidents rarely result from a single cause but rather from a sequence of situations where various contributing factors align to set disaster in motion. Individually, these factors may seem inconsequential, but when combined, they can escalate into major incidents. Understanding these interconnected aspects can help you transition from reactive responses to proactive accident prevention.

A recent case study involves a ground collision (see visual reconstruction) at Atlanta airport on 10-Sep-2024 between a Delta Air Lines Airbus A350 and a Bombardier CRJ-900 regional jet. While taxiing, the A350’s right wingtip struck the CRJ-900’s vertical stabilizer, resulting in significant damage to the smaller aircraft and minor damage to the A350. The incident remains under investigation, with preliminary findings suggesting that communication gaps, ground movement protocols, and situational awareness issues contributed to the collision.

• CRJ-900 Positioning. While taxiing for departure, the Endeavor Air/Delta Connection CRJ-900 stopped 56 feet short of the designated hold short line on the taxiway. Although it could have positioned closer in preparation for entering the runway, its position did not violate procedural regulations, which only require that no part of the aircraft extend beyond the hold short line, without specifying a minimum stopping distance. However, had the CRJ-900 taxied closer, the collision with the passing A350 could have been avoided.
• A350 Crew Distraction. While taxiing on an intersecting taxiway, the A350 flight crew detected a maintenance alert on the dashboard. They requested permission to stop on the taxiway to promptly investigate the issue and consult with company maintenance. However, ATC, likely prioritizing traffic flow, denied the request and instructed them to continue past the CRJ-900 before stopping again. Despite this, the crew chose to address the alert while taxiing, leading to a distraction at a critical moment as they passed the other aircraft.
• Situational Awareness Challenges. Preoccupied with the maintenance alert, the A350 pilots failed to notice the close proximity of the CRJ-900. The cockpit also included two relief crew members—the relief captain and relief first officer—who, like the primary crew, failed to recognize the risk. Positioned on the starboard side, it was the first officer’s responsibility to ensure sufficient clearance. However, distractions impaired their situational awareness and decision-making. Standard protocol dictates that, when in doubt about clearances, pilots should stop, set the brakes, and address issues without multitasking.

As mentioned earlier, the incident is still under investigation, but I believe the ultimate responsibility for avoiding obstacles lies with the distracted A350 crew. Although they followed ATC instructions and stayed on the taxiway’s centerline, the crew should have remained more vigilant. Neither ATC nor the A350 crew noticed that the CRJ-900 was positioned in a way that prevented the A350’s wingtip from clearing it.

Given the limited visibility of the wingtip from the A350 flight deck, it’s pilots should have stopped if they were unsure about clearance. This event highlights the need for improved Crew Resource Management (CRM) training to enhance teamwork, decision-making, and vigilance. Standard procedures emphasize stopping, setting the parking brake, and seeking assistance when obstacles are suspected. Flight crews must maintain spatial awareness and heightened perception of surrounding aircraft, even while managing other operational tasks.

Idea for Impact: Recognizing accidents as the result of interconnected contributing factors emphasizes the importance of addressing not only individual issues but also how they interact within the system.