Originally Posted by TopBunk
In any accident there are primary causes and contributory factors
TopBunk,
I believe the ICAO agreement requires countries to identify a "probable cause" of an accident. Since most investigators realise that there is almost never just one cause of an accident, many jurisdictions now speak of "probable cause and contributing factors", and I understand the Canadians don't prioritise at all.
Most top researchers in accident causality judge that prioritising causes, as it is now performed by investigating authorities, is a matter of ranking causes according to inexplicit criteria which may be extraneous to causally explaining the accident.
Could you give your criteria for selecting "primary cause"?
Could you say, for example, why you would not consider the length of the runway as a "primary" cause? It does satisfy the Counterfactual Test, just as your chosen "primary" cause does. Why do you pick one but not the other?
One selection criterion could be: we reckon relative persistence of the phenomenon throughout successful operations counts for a lower priority. The length of the runway certainly fits this criterion for deselection - it has been used in many successful landings, including one just before the accident. So we would reckon that priority as low (as, for example, the earth bank at the end of the runway was not reckoned as a causal factor in the Warsaw report, even though it was directly causal in the two deaths that occurred), and the pilots' (in)actions in not reducing TL to idle as high.
The problem with that criterion is that it allows unsafe situations that persistently recur to achieve low priority automatically. For example, AA was warned in 1997 by AI, Boeing and the FAA in a joint letter that teaching use of rudder in their advanced piloting course could possibly lead to structural failure of an aircraft. Which happened in 2001. So this persistent phenomenon which some considered unsafe would be discounted as a causal factor according to the criterion above.
An obvious, and obviously not scientifically justifiable, selection criterion is: we discount phenomena which were "our" responsibility, and we emphasise phenomena which were the responsibility of others. This is why, for example, in many countries the investigating body is structurally independent of other government authority, for then there is not seen to be the "our"-"their" distinction on which this criterion rests. Examples of this might be (1) Warsaw; (2) in the inquiry into AA587, the NTSB Chairman complained publically about persistent interventions by the two main organisations involved in the accident; (2) concerning the 2006 Amazon midair collision, there has been suggestion by some authorities that air traffic control is not a factor, although the behavior of individual controllers might have been, despite that the displayed altitude of the Legacy on the controllers' screens at CINDACTA-1 was different from the altitude at which it was actually flying. And the investigating body is a part of the same government organisation which has responsibility for air traffic control.
PBL