The Boeing FCTM makes an interesting point about releasing the brakes if you are going sideways in reverse during the landing run on a slippery runway with crosswind. Among other things it states: "To correct back to the centreline, reduce thrust to idle reverse and release the brakes". It also says "Main gear tire cornering forces available to counteract this drift are at a minimum when the antiskid system is operating at maximum effectiveness for the existing conditions."
So you have the situation where a slippery runway has a crosswind and normally the pilot would select an appropriate autobrake setting depending on landing weight and runway length. You plant the aircraft beautifully at the 1000 ft markers and apply full reverse (reverse is most effective at high speed) and you think the autobrakes are working but it is initially hard to tell on a slippery runway. They are probably working but the decelleration is hard to feel although you could have a quick glance at the green line going backwards on your glass cocpit ADI.
A sideways drift hits and the aircraft weathercocks. The book says to go to idle thrust (ever tried to reduce to idle thrust quickly without coming out of reverse completely - you need lots of practice I tell you).
The N1 is spooling down and you quickly dab hard on the downwind brake in order to straighten up. That dab immediately disconnects the autobrake system and the aautobrake disarm light comes on. Chances are the PNF does not notice the autobrake light illuminate because he is sweating on you straightening the aircraft before it slides off the edge. You didn't see the light come on either, because you too are sweating on trying to straighten up.
The aircraft now is hopefully straightening up under the influence of your dab of the downwind brake pedal and you relax knowing the autobrake is working hard to pull you up - except it has been inadvertently disengaged by your little dab. Now tracking straight you rip back into reverse but it takes a long time from 23 percent N1 in idle reverse to wind up to 89 percent or full reverse. No problem with a long slippery runway but a real bind if it is a limiting length runway.
Let's go back to the advice contained in the FCTM. How would you interpret that advice with regards to the words "Reduce reverse thrust to reverse idle and release the brakes."
Does this mean you switch off the autobrakes? If so, what is the fastest way of doing that? Override by depressing hard on the brake pedals - or maybe having the PNF turn the autobrake selector off? Or perhaps put the speed brake lever in the down detent which turns off the autobrakes? The latter is a bit of a risk because you need spoilers to dump lift and put weight on the mains.
It all becomes a bit convoluted doesn't it. The tricky part as I see it is deciding in a flash how to take the brakes off as you are going sideways. Makes for a good discussion.