ATSB identifies firefighting helicopter safety risks after Bell 412 incident

An Australian Transport Safety Bureau (ATSB) investigation has identified shortcomings in operational risk assessments and aircraft configuration following an incident involving a Bell 412EP firefighting helicopter in Tasmania.

The Coulson Aviation Australia-operated helicopter, owned by the New South Wales Rural Fire Service (NSW RFS), was conducting aerial firefighting operations near Canning Peak on 10 March 2025 when it unexpectedly descended approximately 50ft while filling a water bucket from the Murchison River.

The helicopter was hovering about 150ft above the water when the descent occurred. The pilot recovered to a stable hover but was unable to release the suspended long line. The subsequent loading of the line, caused by the submerged bucket, brought it into contact with the helicopter, damaging the airframe and flight control systems.

Despite experiencing flight control difficulties, the pilot returned to a refueling base and landed safely. An inspection identified substantial damage to the helicopter’s underside and flight controls.

Aerodynamic and operational risks

The ATSB found that the pilot had approached the water collection site in a steep descent at low forward airspeed with power applied. These conditions were likely conducive to an incipient vortex ring state (VRS), also known as settling with power, or a combination of the two, contributing to the uncommanded descent.

Investigators also identified limitations in the configuration of NSW RFS Bell 412 helicopters that reduced pilots’ visibility of suspended loads.

External forward-looking infrared (FLIR) cameras and extended flight steps, where fitted, obstructed the view of the bucket and long line, prompting pilots to adopt steeper approaches that increased exposure to the aerodynamic conditions associated with VRS.

The investigation further found that Coulson Aviation Australia’s flight risk assessment tool (FRAT) did not adequately capture mission-specific and aircraft-specific hazards associated with aerial firefighting. Problems with the tool’s design, application, and oversight limited its effectiveness in identifying and managing operational risks.

ATSB Chief Commissioner Angus Mitchell said: “These factors reduced the FRAT’s effectiveness in identifying and managing operational risk.”

Following the investigation, Coulson and NSW RFS began reviewing the helicopter’s extended flight steps and working to improve consistency across aircraft systems, cockpit layouts, avionics, and pilot interfaces.

Coulson has also initiated improvements to its flight risk assessment procedures to better account for operating environments and mission-specific hazards.

Mitchell said operators should ensure pilots have appropriate risk assessment tools to identify conditions that increase exposure to VRS or settling with power. He warned that obstacles, low airspeeds, high power settings, and limited recovery options could increase the risks during firefighting operations, particularly when approaching water sources in confined areas.