Grenfell: How to investigate what happened

"Whatever the mechanism, it is vital that we understand the causes of this accident"
"Whatever the mechanism, it is vital that we understand the causes of this accident"

Andrew Blackie was an Air Accidents Investigation Branch (AAIB) operations inspector from 2007 to 2017. Here he outlines various options for how to investigate what took place at Grenfell.

By Andrew Blackie

There has been a lot of discussion about how the investigation into the Grenfell Tower fire should proceed in the wake of the tragedy. Every day that debate becomes more politicised. In order to come to a sound judgement on it, it's worth taking a look at the various models on offer, so that we can assess them for speed, purpose and independence.

Disaster investigations in the UK depend on what sort of incident it was. Some are done with the intention of prosecution or determining liability, others are purely for learning and others are a hybrid. 


Aviation around the world separates its safety investigators from its regulators and prosecutors. In the UK, drawing on our experience in aviation investigations, our rail and marine sectors adopt a similar approach. The first investigation is the one that tries to learn lessons and protect lives in the future. Other investigations continue in parallel but with boundaries and good liaison to ensure everyone is clear about the different purposes of the different investigations.

Air Accidents Investigation Branch (AAIB) investigations tend to work well because they step outside the blame cycle and try to understand not just where things went wrong, but why what people did made sense to them at the time. 

Final reports are typically published between six and 24 months after the event, but short initial bulletins are usually produced very quickly following major events. In the case of the Shoreham Airshow disaster in August 2015 the first short report was released 13 days later.

When changes that could improve safety are identified in the course of the investigation, special bulletins containing recommendations are published without waiting for the final report. At Shoreham, an engineering-related special bulletin came out four months after the accident and included seven safety recommendations. A 27-page, public-safety focused report including 14 safety recommendations was published in March 2016, in time for the 2016 air display season. The final AAIB report, of over 400 pages, was published in February 2017, 18 months after the accident.

While these timelines may seem long, the relevant parties are kept informed of identified safety issues.  Where organisations can take safety actions they should do so without waiting for the final report.

The key point here is that AAIB reports are freely published and can be read by anyone with an interest in the case. This openness is moderated. Certain types of evidence, such as witness statements, are protected by statute and there is a tricky balancing act between the need for the investigation to use the best, most reliable evidence and the desire for the public to have access to source information.

Disaster investigations sometimes find that all the individual elements of a project were compliant with their own specific standards but that the interaction between them, and how that changed the overall risk picture, had not been considered. Operational procedures which were correct at one time can be dangerous when the system is changed. Often the users of the system don’t know that the technical alteration means they now must respond differently. This is not unusual in accidents seen in a range of industries. Understanding these interactions requires a systems approach - a methodology which is often poorly understood.

In other fields we have also seen complex regulatory arrangements leading to confusion about ownership of risk and diffusion of responsibility among otherwise competent authorities, organisations and individuals.

Any or none of these factors may be involved at Grenfell Tower. 

It is a significant challenge for investigators to build a picture of the system as it was. It relies on both the expertise of the investigators and openness from the parties involved in an incident.  That openness is far from guaranteed and separating the investigation of blame from that of safety is intended to encourage those being investigated to be open. 
It is also possible that one or more elements of the Grenfell build may not have been compliant with a relevant standard. This is not unheard of in transport accidents and is normally due to error rather than malice. A well-designed safety system will compensate for this by having layers of control to capture errors and by being tolerant of failures within different components when they do happen. 

Safety is not the absence of accidents, it is the presence of defences and capacity. Defences tend to be based around the pre-planned or predictable events whereas capacity is the ability of the system to deal with the unexpected and both remain acceptably safe and to recover. There will undoubtedly be much debate in the coming months about the physical defences to fire which were or were not present in the structure.  But we should also consider the capacity of the building, its systems and people's response when the fire behaved in an unexpected way. 

All of this leads to a question of who has the expertise to conduct the investigation while having sufficient independence to maintain the confidence of all the involved parties. The London Fire Brigade have both expertise with fires and public confidence. But they also seem to have had some involvement with the risk management process, advising the council and conducting fire safety checks. They are also involved in bringing prosecutions and this may affect the willingness of witnesses to speak with them.
There could be similar concerns about public bodies such as the Health and Safety Executive (HSE) despite their renowned capability in both the technical aspects and human factors surrounding incidents.

Perhaps unsurprisingly it has been decided that a public inquiry will take place for Grenfell Tower along with various other investigations, including those by the police. The scale of destruction and loss at Grenfell Tower is similar to that you'd expect from a major transport disaster and, although a public inquiry was once the normal approach in those cases, the UK has steadily moved away from them for transport accidents.

Recommendations from the Ladbrook Grove inquiry in September 2000 led to the formation of the Rail Accident Investigation Branch in 2005.  This was an echo of the Marine Accident Investigation Branch which was founded in 1989 following the 1987 loss of the ferry Herald of Free Enterprise.  There has not been a rail, air or marine public inquiry since 2000. 

Where a broader process would sit, what sort of things it would do and how it could be funded is complicated. The current accident investigation branches are not expensive in government terms, but they are not free and there is always a balance between the cost of these capabilities and what they return in terms of safety improvement and answers for those involved. 

It's worth having a look at what they do in Holland for an alternate model.  The government-funded Dutch Safety Board (DSB) describes its remit as investigating accidents where "civilians are dependent on the government, companies or organisations for their safety".  In an increasingly complex society, we are all dependent in one form or another on government, companies or organisations. The promise of an independent, effective safety investigation can form part of the social contract between the state and its citizens. There is no doubt that the DSB description of dependencies applies to the residents of Grenfell Tower and many other blocks like it.

Whatever the mechanism, it is vital that we understand the causes of this accident, both at the proximate level and the regulatory and societal mechanisms that allowed those causes to exist. We must do this to not only give answers for those who have been affected but to improve public safety.

Andrew Blackie was an Air Accidents Investigation Branch (AAIB) operations inspector from 2007 to 2017. He is now an independent consultant at Abris Consulting Ltd as well as a visiting fellow in Safety and Accident Investigation at Cranfield University.

The opinions in politics.co.uk's Comment and Analysis section are those of the author and are no reflection of the views of the website or its owners.

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