My most alarming approach onto SFO 28L was once with the F/O flying the approach (perfect VMC) on the 28L ILS with an MD80 a few hundred metres ahead on approach to 28R. My F/O was flying completely "heads down". On my making the remark, "keep an eye on the other aircraft", he got such a shock that he immediately pulled up and rolled left, about 20 degrees off runway alignment. I SHOULD have gone around, but as we were 20 degreea pointing away from the approach, eased the nose down, re-sighted the other aircraft, and, having taken control, I then rejoined and flew the remainder of the approach.
SEE AND BE SEEN!!!!!
Regards,
Old Smokey