Usually, this tactic is used to counter the highly popular, and fucking hilarious, roadkill tactic, and in team games is often used as a form of vehicular manslaughter.
Unfortunately for the BW'ers, the Banshee sucks total ass, and is an easy target for the Warthog's rear-mounted minigun.
DataLord: "suck minigun, fucktard!"
t3h_sniper got wasted.
Kouen: "banshee whoring. what a newblet."