Sixteen people set off in a carriage on the Smiler ride at Alton Towers on 2nd June last year.

Minutes later, their carriage smashed into the rear of a stationary carriage, resulting in all of them suffering injuries, five seriously. Of these, two teenage girls, Victoria Balch and Leah Washington, had to have legs amputated.

The theme park operator, Merlin Attractions Operations Ltd, stated in the press afterwards that the accident was down to “human error”. “A ride shutdown message was misunderstood by staff at the ride,” said an Alton Towers spokeswoman. “This led to a decision to manually restart the ride, overriding the control system without appropriate safety protocols being followed correctly.”

A classic example, sadly, of shifting the blame onto individuals. Blaming the accident on unsafe acts and unsafe conditions, such as employees over-riding safety devices, is all too familiar. This approach is almost universally adopted in the aftermath of an accident.

To find out the true cause of any accident, major or minor, it is necessary to trace back the sequence (often known as the “Domino Theory” of accident causation). This will inevitably result in a different conclusion being made, that of a failure of management systems.

In the case of Alton Towers, following an exhaustive investigation, the HSE successfully argued that, rather than the accident being caused by “human error”, the fault was with the employer, not individuals.

The court had heard on Monday how engineers failed to notice a carriage that had stopped midway around the 14-loop ride. They assumed there was a problem with the computer and over-rode the stop mechanism setting another train in motion and into the empty carriage.

The prosecution case identified that workers had not been given a system to follow which would safely deal with the issue. Engineers had not read or seen the ride’s operating instructions. It was also pointed out there were estimated winds on the day of the crash of 45 mph, but the manufacturer’s manual stated the ride should not be operated at wind speeds above 34 mph. An alarm designed to sound when wind speeds exceed 32 mph did not sound.

All these issues are management failings, or root causes, rather than individual or human failure.

In April, Merlin admitted breaching the Health and Safety At Work Act 1974. Today, they were sentenced to a £5m fine, and ordered to pay costs of £69,955.40.

During sentencing, Judge Michael Chambers QC, who described the crash as a “catastrophic failure”, said human error was not the cause as was suggested at first. He also remarked that “this was a needless and avoidable accident in which those who were injured were lucky not to be killed,” he said.

In mitigation, Judge Chambers acknowledged that the defendant had taken full and extensive steps to remedy the problems that led to the accident. Since the crash, a number of safety changes have been made including a policy of closing the ride when winds exceed 35 mph.

Nick Varney, chief executive of Merlin Entertainments, said they were determined to “never repeat” the devastating accident and stressed the firm was not an emotionless corporate entity.

In the aftermath of the accident, Alton Towers saw a steep drop in revenue and visitor numbers.

Braeside Safety offer health and safety consultancy services, as well as a range of training including short courses on senior management responsibilities, accident prevention and accident investigation.