NDT's are terrible on ice. Best if you can air way down to get at least a little of the H's edges on the pavement.
Sometimes 4wd is not advised on ice. If there is any chance of sliding sideways, or if a turn is in progress, the tires will hold better if not driven. Locking differentials will guarantee a sideways slide.
Consider the common knowledge that driving in 4wd on hard pavement causes severe binding and even breakage. That's because the tires will be forced to rotate at different speeds when turning, or even when rolling straight ahead if the rolling radius of the tires is different. Now consider the same scenario on ice. Sure do not want to be forcing the tires to slide! So many times it's better to creep through without 4wd if you can get enough traction.
For braking, however, 4wd and very light petal works best. That's because the brakes will never actuate equally, at the same time. The first brake to apply will slide. Then the 2nd, 3rd, etc, tires will slide. But in 4wd with all corners mechanically connected, braking force from that first brake will be applied through the driveline to other tires, applying equal braking force to all tires.
Sounds backwards, doesn't it....using 2wd to go, 4wd to stop.
BTW, an automatic tranny vehicle will stop much better if you bump the tranny into neutral before stopping. Otherwise the transmission is trying to power the rear wheels forward while you are trying to stop front axle (which does majority of braking).
tennmogger