missing the issue

Why do careful organisations sometimes miss really important uncertainties? The answer often involves some mix of

using a 'checklist' approach to identify issues
a brainstorming approach which missed something
a systematic 'work through everything' approach that ran out of steam, or
an issue HAD been identified but turned out to be a sub-set of a bigger issue (of which another, different sub-set then actually turned up).

Checklists

These are great if what you're dealing with is exactly similar to the organistion or activity, and the scope of issues, for which the checklist was devised. But it's very easy to miss critically important uncertainties that are specific to YOUR particular organisation, activity or scope of concerns.

Brainstorming

This is an important part of most issues identification processes. But as well as getting the right people involved, it needs system and structure to come out with a set of issues that are comprehensive, without being so voluminous as to be unmanageable.

Systematic Working Through

Well-known techniques such as HAZOP and Failure Modes and Effects Analysis provide a structure to make brainstorming more effective. The main problems we find with the results of such approaches are

large volumes of issues that are difficult to prioritise, and
issues defined at different levels with potential for gaps and/or overlaps.

"we spotted a similar issue but missed that one "

This is often the result of an exercise that identifies issues at many different levels but can leave gaps and overlaps. For example we may have spotted the issue

"Protection system was in a failed condition",

but failed to realise that this was a sub-set of the bigger issue

"Protection system didn't work for whatever reason".

The latter includes possibilities such as the protection system not being up to scratch, or being turned off, which might be just as important - if not more so - as the protection system having failed.

Avoiding the Pitfalls

Our preferred approach is to combine elements of all of these ideas but to add some important elements including

up-front clarification of what matters to the organisation and why
top-down as well as bottom-up brainstorming ("How in principle might this happen?" as well as "What if XXX went wrong?")
organising identified issues into a simple hierarchy, and
rough but evidence-based quantification from the outset.

Follow the green links above to read why we think these are so important.