A study initiated to support the ATSB's investigation into the midair collision between two helicopters on the Gold Coast demonstrates the cockpit visibility limitations which contributed to the accident.
On 2 January 2023, two Airbus EC130 helicopters collided over the Gold Coast Broadwater, resulting in four people being fatally injured, six people sustaining serious injuries, and three people sustaining minor injuries.
In the course of its investigation into the accident, the ATSB sought to identify what limitations or opportunities the pilots had to visually detect and avoid the other helicopter.
"This Cockpit Visibility Study sought to gain a more detailed understanding of whether the 'see-and-avoid' principle, with its known limitations, could have effectively helped the pilots avoid the collision," ATSB Director Transport Safety Dr Stuart Godley explained.
The study involved a review of available literature, the development of a detailed three-dimensional model of an exemplar EC130 B4 helicopter, and a detailed analysis of onboard data from both helicopters.
It also incorporated the development of an animation in collaboration with Airbus Helicopters and a simulation expert at iwiation GmbH in Germany.
"Throughout the development of the study and accompanying animation, multiple data verification processes were employed to ensure - within the limitations outlined in the report - the analysis aligned with actual events," Dr Godley outlined.
"This included cross-validation between the visibility study analysis and animation (which were developed using separate techniques), as well as validation of aircraft position and orientation using footage from multiple external cameras, and validation of these factors, as well as pilot eye positioning, using camera footage from inside each helicopter."
The resulting paper concludes it was unlikely either pilot could have detected the other aircraft at critical times in the lead-up to the collision.
"This was primarily due to obscuration from the aircraft structure," Dr Godley said, "but it was also impacted by the relative position and visual size in the simulated pilots' field of view, pilots' apparel, environment, and aircraft fitment."
Dr Godley said the study reinforced the known limitations of see-and-avoid - serving not just this investigation, but as a reminder to all pilots.
"Visual acquisition is a primary tool for pilots to assist them in locating and identifying traffic around them, but as this study and a volume of previous work demonstrate, its effectiveness is limited by a number of factors," Dr Godley said.
"Pilots need to be aware of these limitations, and how they can offset them with effective communications, onboard electronic systems and visual conspicuity devices."
The ATSB's SafetyWatch initiative highlights broad safety concerns generated by its investigation findings, and from occurrence data reported by industry.
One such safety concern is Reducing the collision risk around non-towered airports. The linked page gives several other examples of issues and accidents that have occurred around non-towered airports and provides guidance on how pilots can keep themselves and others safe.
You can find here the safety study: Cockpit Visibility Study supporting AO-2023-001 - Midair collision involving Eurocopter EC130 B4, VH XH9, and Eurocopter EC130 B4, VH-XKQ, Main Beach, Gold Coast, Queensland, on 2 January 2023
