This thread has reminded me of a very interesting TV programme I saw recently entitled "How we make decisions." Here's a brief, edited, summary.
With every decision you take, every judgement you make, there is a battle in your mind - a battle between intuition and logic.
And the intuitive part of your mind is a lot more powerful than you may think.
We like to think that our beliefs, judgements and opinions are based on solid reasoning. But we may have to think again.
Prof Kahneman realised that we actually have two systems of thinking. There's the deliberate, logical part of your mind that is capable of analysing a problem and coming up with a rational answer. This is the part of your mind that you are aware of. It's expert at solving problems, but it is slow, requires a great deal of energy, and is extremely lazy.
But then there is another system in your mind that is intuitive, fast and automatic. This fast way of thinking is incredibly powerful, but totally hidden. It is so powerful, it is actually responsible for most of the things that you say, do, think and believe.
Most of the time, our fast, intuitive mind is in control, efficiently taking charge of all the thousands of decisions we make each day. The problem comes when we allow our fast, intuitive system to make decisions that we really should pass over to our slow, logical system. This is where the mistakes creep in.
Our thinking is riddled with systematic mistakes known to psychologists as cognitive biases. They affect our beliefs, our opinions, and our decisions, and we have no idea it is happening.
It may seem hard to believe, but that's because your logical, slow mind is a master at inventing a cover story. Most of the beliefs or opinions you have come from an automatic response. But then your logical mind invents a reason why you think or believe something.
Those wondering what I mean, please bear in mind the quite stunning paucity of
FACTS in the case of Chinook ZD576!
Please allow me to summarise them for you:
1) Ground witness marks at the accident sight.
2) Physical wreckage, of which (as I was corrected) 20% was destroyed, and 80% affected by the post impact fire.
3) precise positions of components in the flight control system at the moment of impact, including the Differential Air Speed Hold, and the Longitudinal Cyclic Trims.
4) Approximately three or four items of data from Supertans. This data was simply 'snippets' of information used by the navigation computer in the course of it's ongoing calculations. Non linked to each other. Supertans was never designed to provide historical data, nor has it's accuracy in that mode ever been verified, however at least one of those 'snippets' was demonstrably wildly inaccurate.
5) Weather reports from walkers on the Mull who described hill fog. The only weather report which had any bearing whatsoever on conditions from the cockpit came from a lady with a sea view from Antrim, and a yachtsman. Both of whom could clearly see the coast around the Mull, and conditions of bright sunshine.
I am unaware of anything else
FACTUAL, though I am prepared to be corrected.
What there was
NOT, is Flight Data Recorder, Cockpit Voice Recorder, survivors, eyewitnesses, radar traces, or radio conversations, though one call from F4J40 did go unanswered.
From this limited evidence, the BOI, had no choice but to resort to a computer model which was constructed in an attempt to tie together the dirth of factual information in a possible scenario which might 'fit'. This model was only ever designed to model the final 3.9 seconds of flight, but from a pre-existing trajectory.
3.9 secs! No more!
Apart from this there is no other evidence.
Against all this there is the fact that no versions of RAF Chinook we're recommended for low level flight due to problems with DASH which had caused numerous UFCMs. Chinook Mk2, and ZD576 in particular, was an extraordinarily unreliable machine, with very serious flight control and FADEC faults, both of which we're evident in the wreckage. Much later it has been discovered that Mk2 was not even cleared to fly, having 'switch on' clearance only. This was a criminally immature development.
So what could possibly have caused the accident? As far as I'm concerned it's anyone's guess. UFCMS due to DASH or flight control faults? (seen previously in ZD576
AND in the wreckage) Absolutely. FADEC malfunction which would have left no physical trace? Absolutely. CFIT? Absolutely. Powerful visual illusion? Absolutely - it caused a previous RAF Chinook fatal accident, and is another form of CFIT I guess.
All I would counsel is, never forget that 'absence of evidence' is NEVER equivalent to 'evidence of absence' and this case could almost have been designed to demonstrate that precise concept!
When you have such limited evidence, how can you even begin to assess the probability of each possible cause? How can you determine which was 'most' likely, and frankly what's the point? Not flight safety that's for sure! Very occasionally we may have to accept, we'll never know for sure. That's a tragedy to all concerned, and the responsibility for that lies with those choosing not to fit FDR and/or CVR. Not those at the controls of the aircraft!
Finally I refer you back to the quote I commenced with:
Your logical mind is a master of justifying what your intuitive mind has 'decided'!
For me, there is insufficient reliable evidence to reach any reasonable conclusion. Others think differently. That's fair enough, but they are now opining beyond what is officially accepted. It may occasionally be necessary to accept we will never know what caused certain accidents. That is a tragedy for those involved, but the responsibility for that inadequacy lies squarely with those responsible for decisions not to fit CVR/FDR. Those at the controls of this aircraft have lost their lives, they shouldn't also be required to lose their reputations simply due to the decisions of others!