There is another way that you can do that without haveing the risk of dying. You but the tank on one of the top areas (where theres an opening in the natural wall) and put the tanks back against the inside. it wont go all the way in. then you take a ghost and run straight at the tank. youll pop up on top and still have a ghost with you fro speedie transportation. this takes lots of practice and even more patience.

I have this trick in sidewinder when i play with teams. I put the tank next a wall and i get inside a ghost. My team mate sticks a plasma grenade on the back of my ghost and i drive towards the tank. Then the plasma grenade explodes and im in the air. It is like the ultimater base all grenades are duds and most bullets miss and the enemy cant find you

my favorite would have to be blocking the entrances/exits with vehicles on blood gulch CTF, or jumping through the windows at red base in Battle Creek CTF...the latter can grab your three flag captures nearly undetected in about 2 or 3 minutes.