Near miss with 5 airliners waiting for T/O on taxiway "C" in SFO!

[WillowRun 6-3]

Figuring out causal links (plus a question)

A set of factors led up to this incident, and obviously not all of those factors yet are identified, let alone integrated into an overall narrative - but will the end result of the Board report be fully satisfactory? To explain . . .Reference has been made by several posts to the Colgan accident, as I understood it, for context for suggestions that effects of fatigue, or circadian rhythms (or both), played a role in the SFO incident. Someone posted the NTSB report on Colgan which I took as an invitation to start reading said report. Immediately the role of probabilistic assessment leapt out from its pages:

"The National Transportation Safety Board determines that the probable cause of this accident was the captain’s inappropriate response to the activation of the stick shaker, which led to an aerodynamic stall from which the airplane did not recover. Contributing to the accident were (1) the flight crew’s failure to monitor airspeed in relation to the rising position of the lowspeed cue, (2) the flight crew’s failure to adhere to sterile cockpit procedures, (3) the captain’s failure to effectively manage the flight, and (4) Colgan Air’s inadequate procedures for airspeed selection and management during approaches in icing conditions." Report Sec. 3.2 (p. 155).

Note also, Finding no, 9, the reason the captain failed to recognize the impending onset of stick shaker “could not be determined from the available evidence”; Finding no. 15 (“the reasons the F/O retracted the flaps and suggested raising the gear could not be determined from the available information); and Finding no. 24 (“The pilots’ performance was likely impaired because of fatigue, but the extent of their impairment and the degree to which it contributed to the performance deficiencies that occurred during the flight cannot be conclusively determined”).

It seems more than just reasonable to say that the analysis of causes in the AC 759 SFO incident also will involve a set - a complex, a list - of factors. What is the standard for "probable cause" as opposed to a "contributing factor" as opposed to some factor that a large or even vast majority of ATPs will say was a relevant one but which the available evidence or information does not warrant making a firmer conclusion or finding about? More than a pedantic query, the standard for assessing causal linkage relates directly to identifying priorities for rule-making, technological system assessments, and other factors. (And is formal assessment of cause one which assumes that all of the factors would take place in the next potential incident or does the remedial and preventative effort proceed with an understanding that several different combinations of most, but not necessarily all, of the factors would result in an accident the next time?)

The glib reason for being curious about this is that as Congress and other interested parties take a shot at separating the ATC and Safety functions of FAA, the agency's ability to respond to NTSB recommendations certainly cannot be allowed to be degraded, downgraded or otherwise reduced, and should instead - in such a legislative initiative - be significantly improved.

Now, does anyone who actually flies such an aircraft on such an approach as was involved in this incident think that the actual physics of the situation - the amount of actual distance between two potential points of contact - was a result of some lingering doubt in the mind of the PF that maybe the approach had been screwed up, misaligned? In other words, did PF possibly fly the approach just a little bit higher, out of some kind of PF muscle memory, let's call it, just because something didn't seem quite right? The margin was so small, was it not? - but was it "enough" because the PF left a tiny bit of extra margin, subconsciously if that is what you want to call it?

Edit: Statement of Chairman Hersman, concurring (Colgan report): "We . . . do not require that any causal or contributing factor equate to a percentage or share of the cause of an accident."
(Notation 8090A, pg. 3)