PAPIs and VASIs were installed at airports all those years ago to enhance safety as they are aids in ensuring a stable approach during the visual segment of an approach to landing.
SFO 28L/R G/S have been Notamed out for the last 3 weeks and despite that, pilots from all different airlines and countries have done hundreds of visual approaches without incident.
So sure, the average airline crew is supposed to be able to do a visual approach to landing without an issue. However if Accident and Incident reports tell us one thing, its that they happen when we least expect them to and the reasons for their occurrence ranges from the sublime to the ridiculous.
Coming from the west, they would have been vectored for the downwind. If they found them selves high turning base they would have been busy trying to "get back into the slot". Without the traditional vertical guidance of the G/S and PAPI, it takes a little more brainwork (using their FMS or handy 3 in 1 rule would have helped) to make it all come together. However, if they haven't done any raw visuals in recent times it is possible to lose Situational Awareness (positional and operational) during the resulting "Arms and Elbows" moment.
In our business, Mr. Murphy is always lurking not too far in the background and with these safety enhancers unavailable, Statistics and Probability once again formed an alliance and the dreaded Swiss Cheese holes lined up, resulting in what looks to be an undershoot in this very Lonnnngg and Heaaaaavvy 777. (Go Around at Company Mandated Alt)
This is all speculation of course but I just can't see this accident happening if the ILS and/or PAPI was operational in SFO. My 2 cents.
But for the Grace of God go I....
Last edited by Jasavir; 7th Jul 2013 at 07:39.