Assault class is the first class aviable in the game. It's also the class we play as in the tutorial. On default assault is an australian male equipped with Auto Rifle, Pistol, Repair tool, Frag grenade and as an ability: Jetpack.
Assault's jetpack is a movement ability that (if he is still on the ground) launches him upwards like a super jump and then allows him to hover above the terrain for considerable ammount of time. This ablility can be enhanced via skill tree to FE: last longer, increase movement speed, etc.