This is a preliminary Bow-Tie analysis of the recent Air Canada 759 Severe Incident at SFO.
From the preliminary NTSB Report (DCA17IA148 web available) and audio file, we can only assume which was the possible scenario.
Considering that:
1 - We do not know yet if any Notams were active at SFO;
2 - WX was certainly not a factor;
3 - Flight Crew deliberately chose a Visual approach by night;
the most probable causes of the "Undesidered event" have to be found in the failing of Causal Barriers B2, B4, B5, B6 (almost all Human Factor related).
Fortunately Consequential Barriers C1 and C2 worked properly, although we strongly believe also C3 would also have.
Standing by for final report.
Any comments welcomed.
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