The Australian Transport Safety Bureau today published their final investigation report into the January 2023 collision between two helicopters at Sea World on the Gold Coast.
Two Sea World Airbus EC 130 helicopters, VH-XH9 and VH-XKQ, collided on scenic flights resulting in the death of three passengers and one pilot, and injuries to the second pilot and another five passengers.
XH9 was inbound to the Sea World helipad and XKQ departing from a separate helipad at Sea World when they collided only 130 feet above a sandbar. XKQ went out of control and crashed onto the sandbar, whilst the pilot of XH9 managed to make a controlled emergency landing on the sand despite the extent of the injuries and damage.
ATSB investigators determined that the rotor blades from XKQ passed through the forward cabin of XH9, and the forward cabin then collided with the fenestron on XKQ, causing XKQ to break-up inflight and crash onto the sandbar.
The investigation was one of the most complex the ATSB has ever done, and resulted in investigators identifying 28 safety factors.
Most prominent were the discovery that a defect in the radio on XKQ could have prevented the pilot of XH9 from hearing a taxi call, the positions of each helicopter being substantially obscured from each other by airframe components, and simultaneous use of both helipads created a conflict point over the sandbar.
Sea World re-commissioned the second helipad the previous year after it had been closed for three years.
“The most fundamental lesson from this investigation is that making changes to aviation operations, even those that appear to increase safety, can have unintended consequences,” said ATSB Chief Commissioner Angus Mitchell.
“It is therefore critical that changes to aviation operations are managed through the implementation of a defined process to ensure overall safety is not adversely affected.
“In the months prior to this tragic accident, the operator had made changes to improve its tourism product, including commissioning the use of a second helipad location, known as the park pad, the introduction of the larger EC130 helicopters, and new hangar and office facilities.
“Over time, these changes undermined risk controls used to manage traffic separation and created a conflict point between launching and departing helicopters, which is where the two helicopters collided.
“The operator’s safety management system did not effectively manage the safety risk present in its aviation operation, and when numerous changes were introduced, did not implement processes to consider whether they would affect the overall safety of their flights.”
Investigators found that communications also contributed to the crash, with the pilot of XH9 making only the customary inbound calls on Southport CTAF, and a taxi call from the departing XKQ that may have prompted the inbound pilot to broadcast again almost certainly failed due to defects in the comm system on board the helicopter.
"The ATSB found faults in the radio antenna of the departing helicopter which likely prevented broadcast of the taxi call,” Mitchell said.
“Without the taxiing call being received, the pilot of the inbound helicopter, who was likely focusing on their landing site, had no trigger to reassess the status of the departing helicopter as a collision risk.
“This dependency highlights that aviation operations should have multiple safety defences in place and not be vulnerable to single points of failure such as faulty radios, or a pilot's ability to detect another helicopter in a visually constrained environment.”
Visibility analysis done during the investigation showed that the cockpit pillar of XH9 continuously blocked any view of the departing XKQ, and the airframe on XKQ and the pilot's cap peak also prevented the departing pilot from seeing the inbound helicopter.
The investigation details 25 contributing factors to the accident, of which several were identified as safety issues. Among the contributing factors are:
- the pilot of XKQ was busy loading passengers and may not have registered XH9's inbound call
- separation was relying solely on unalerted see-and-avoid
- procedures did not require ground crew to monitor the airspace up to the time of helicopter departure
- the flight paths were dictated by the need to avoid overflying a boat
- Sea World Helicopters was reliant on CTAF calls, ground crew advice, and pilot visual detection of aircraft to ensure separation in VH‑XH9 and VH‑XKQ
- Sea World Helicopters' implementation of their SMS did not effectively manage aviation safety risk in the context of the operator's primary business.
During the investigation, it became apparent that helicopter scenic flight operators were not diligent enough in ensuring seat belts were correctly fitted to passengers, especially when used in conjunction with life jackets.
“While the ATSB was unable to determine to what extent the incorrectly fitted seatbelts contributed to the passengers’ injuries, we know that correctly fitted restraints improve survivability for passengers in the event of collisions," Mitchell said.
“Occupants in helicopter tourism operations world-wide are at risk of increased injury in an accident due to inadvertent incorrect use of seatbelts.”
Investigators also found that the pilot of XH9 had reduced the consequences of the collision by pre-planning, which had previously identified the sandbar as an emergency landing site, and maintaining positive control of the helicopter after the collision.
The ATSB has produced an explanatory video, and the complete investigation report is on the ATSB website.