This is a crane and a skytrack working together. It's a ton of pictures, so they'll be under the fold.
Now they'll unhook the skytrack, and the crane will swing it over to the pad in the containment area.
I don't like it when they use a skytrack because of the danger of using the forks. In My Humble Opinion, they should either twist the forks way up or way down to keep an errant gust from moving the tank and having the forks puncture the tank. Twisting down is the best, because the pallet guard would roll over enough so that the tank would hit it rather than the sharp forks.
This job is also one that I do with my knuckle boom crane rather frequently. The disadvantage of using my crane is that it cannot put someone on top of the tank to unhook the cables or straps like the skytrack can. Plus, they are a lot more maneuverable than my truck. We were set up on the other side of those tanks already set earlier, and it would have been difficult for me to set up in there.
That is a man basket on those forks. It's chained to the guard, and the guy up top you can't see is tethered to the basket and is wearing a hardhat and a safety harness. The cardboard strips are what we use to protect the painted finish from our straps to hold the tanks to the trailer - and when the get wet, they stick.
The other options are for the crane to pick the tank up with two lines on one hook, set it on the ground, then stand it up after unhooking from the sides top and bottom (which are on the top when on it's side), hook to the top, then stand the tank and set it. Some use a really long set of straps, and put a man cage beside where they'll set the tank. Then, they'll drop their hook, and with all the extra slack, drop the hook down the side until another strap can reach the man cage, then pick it up, take the guy to the top, and proceed.
I've even seen guys tape back their safety catch on their hooks, carefully put the hook and strap on the edge of the tank, and slip the hook off the clevis on the straps. OSHA would frown severely on this practice. In the past, some guys "rode the ball" by sitting on the ball above the hook on the secondary line, and ride it to the top, clasping the line with a death grip. I would, anyways. But, those practices are gradually being weeded out, mostly because no one can afford to get caught.
So, just another little procedure we use to offload.