Attack Pattern Beta was a tactic used by Rebel snowspeeders and Mandalorian Alpha-3 Nimbus-class V-wing starfighters in battle.
Behind the scenes
In Star Wars: Galactic Battlegrounds, clicking on a snowspeeder might make him announce "Attack Pattern Beta!"
In Star Wars: The Clone Wars, at the start of the second mission, Mace Windu orders Luminara Unduli to use Attack Pattern Beta.
In Star Wars: Empire at War, one of the things that a V-wing pilot may say while fighting other starfighters is "Commence with attack pattern Beta!"