In my personal experience w/ hydroplaning, most instances resolve themselves almost immediately, as long as the driver doesn't freak out and try to over-compensate. You're driving a very heavy vehicle that wants to be on the ground. If you lose that traction, take the foot off the gas and don't slam on the breaks. The car will get it's traction back. Again, it's when the people around you spaz out and slam the breaks or jerk the wheel real quickly that the problems arise.
I could be completely wrong about this, but it seems to me that every time that I hydroplane it seems to resolve when I let off the gas and simply control the wheel, not overadjust.....Who knows, maybe I've just been lucky.
Now, when it comes to ice or black ice, I have to surrender to the powers that be. Even with experience, you're really just not going to stop a car that's gone into a solid slide on ice. Small patches are one thing, but heaving coverings are another thing. I had seen plenty of cars slide out up in the North in the snow, but that's nothing compared to what I've seen down here w/ the ice storms. The cars really can't correct once they're in a good slide...you just have to bend over and kiss it good-bye. Each year we get to see footage of transit buses sliding into cars and the like. It make for good TV....as long as you're not the one inside.
