Recent discussions have revolved around the man and machine. The inconclusive (different) views reflect the difficulty in defining the problem, together with the natural human dislike of uncertainty. These are further restricted in forum communication, how best to convey judgements with text, especially where these depend on the task being assessed and operating environment, each with a range of interpretations.
There are views of the man or machine, and then the ‘vague’ interface between them. Each attempts to quantify parameters of reliability and/or performance; similarly the concept of average seeks quantity, but most cases the real world the divisions are subjective - uncertain - qualitative judgement. (Skill is not a number, it’s a subjective rating). Numerical or statistical assessments are meaningless without first constraining the contributing parameters.
This is like an experiment judging human performance for a given task (detect trim runaway and act), but where the environment defining the situation is primarily determined by the test subject - the experiment is unbounded. We cannot measure what the crew perceived or ‘felt’ about the situation, or know what they knew - or recalled, or why they acted as they did.
All that might be concluded is that the performance of the single ‘entity’, the human and machine (humach?) in the circumstance was insufficient for the task. The balance of contributions in improving ‘humach’ capability is a judgement, best made within the guidelines of certification and the wide range of experience in that process.
The recent accidents suggest that the overall process for this judgement (certification, design, and test) was flawed; the resultant uncertainty in system failure could not be managed by ‘humach’.
The certification process is being reviewed, thus should identify technical and human aspects to be reassessed, as should be the resultant uncertainty from system failure.
We may not be able to judge any of the above without greater understanding of the original certification, the accident system failure, proposed modification, and most of all the associated justification.
With that, the subjective discussion in this forum and elsewhere could be founded on fact - reducing some of uncomfortable ‘uncertainty’ and need to resort to quantities to describe uncertainty.