The short question: when should it be used?
The longer version. The switch is fitted, but does it actually have a function? It is not mentioned in the QRH as far as I can ascertain, and certainly not in any of the autobrake or anti-skid fault check lists. I know there are a few items on the 3-5 series that are hangovers from the 1-2 series: is this one of them? The 1-2 had a switch for inboard and a switch for outboard antiskid systems so did the 3-5 combine them? I understand what the switch does, but what I don't know is when to use it, if ever, if at all. There is mention of it in the AFM and the Boeing notes and so on, but no mention of when or why it should be used.
As usual your input and experience will be very gratefully received
