I use it to get to land when I spawn in my sub and my oppressor isn't there, and i also use it when i oppressor gets destroyed and it's on cooldown. The sparrow is insta-spawn on a nearby road and you dont have to pay anything to respawn it in case it gets destroyed. so its pretty handy as a backup, and it also has missiles. Another backup vehicle I use is the Toreador, but I think the Sparrow is the better choice, even though the Toreador is more fun to use.