CVR lost!
It is a shame the CVR can not be recovered as it is essential to understand what happened.
The crew has conveniently developed amnesia.
Thinking that 28L was still active when it was on the NOTAM and ATIS Q is to lame.
Not noticing ANY aircraft on the taxiway after passing Uniteds wopping big tail litt with logolight broadside AND the second aircraft suddenly lighting up their aiming point for touchdown , and then claim they saw no aircraft.
That is called selective memory , at best!
Another detail:
There was only one TWR controller, as per procedure. Did he let ground and Clerance Delivery still operate on Ground and then switch you to TWR frequency only when holding short of 28R? One man two frequencies.
This is done some places to avoid congestion on frequency . Is this the case here. That would explain why the second aircraft did not scream blue murder on the frequency. ( Mind you the report would have mentioned if he did call out on ground frqz I suppose )
I suspect had he not put on the landing lights, he would have been dead.
If on Twr , why did he not call out?
Situational awareness is the key , perhaps?
One to land , you are nr two holding short. Relax a bit, all is 100% safe!
To process and comprehend the unlikely picture that someone is about to land on you on your taxiway needs a bit of time and reality checks.
Especially if they did not pay attention to AC last query.
If they just clued in when United piped up and then froze in his landinglights and decided to return the favor and light up their own , then man. was it close.
Funny thing AC pilots claim they did not see this.
Again, we are going to learn a lot from this, I shure have so fare, but it would be great to have the CVR to confirm how it came so close with such an experienced crew.