A BHP rail maintenance crew applied brakes to the wrong locomotive when they tried to help the driver of a runaway iron ore train, which ended up being deliberately derailed in Western Australia's Pilbara region.
The fully-laden, 2.86 kilometre-long train hurtled along BHP's Newman to Port Hedland line for about 50 minutes on November 5, leaving behind driver Peter Frick.
The calamity unfolded after a communication fault between the front of the train and a monitor at the end of the locomotive triggered an automatic brake.
According to a preliminary report released by the Australian Transport Safety Bureau on Tuesday, the driver raised the alarm, applied an "independent" brake and got out to manually apply handbrakes to the 268 ore cars while awaiting help from a maintenance crew.
They were to work from the back of the train, while he was to continue working his way down from the front.
Instead, the crew mistakenly applied handbrakes to an empty ore train that had been instructed to stop and move to a safe place while the emergency efforts were underway.
Meanwhile, the braking system that initially stopped the fully-laden train automatically released after one hour while the driver was still outside.
The train was travelling at 144km/h when it was derailed, destroying two locomotives, 245 ore cars and 2km of track infrastructure at Turner South.
Mr Frick was sacked, with BHP saying initial findings from a preliminary internal investigation showed the accident was the result of "procedural non-compliance by the operator" as the "emergency air brake for the entire train was not engaged as required".
The company also acknowledged "integration issues with the electronically-controlled pneumatic braking system".
Mr Frick has since reached a confidential settlement with BHP after taking his case to the Fair Work Commission.