The OOM pilot battle droid was an OOM-series battle droid used in the Trade Federation Droid Army and, later, the Separatist Droid Army for the purpose of piloting vehicles of various kinds.
OOM pilot droids functioned mostly as the ships' crews of the Trade Federation.
Pilot droids were deployed throughout the Clone Wars, starting from the Battle of Geonosis. The droids played pivotal roles as pilots, saboteurs, and mechanics in tightly contested skirmishes of major battles such as the Battle of Kashyyyk and the Battle of Coruscant. They were also deployed in space battles to man turrets, carry ammunition, and monitor the decks and hangars for breaches and boarding parties. Overall, they weren't part of a separate branch but instead shared by the army and navy. During the Clone Wars, OOM pilot battle droids were part of the crew of Munificent-class star frigates and took orders from organic and OOM droid commanders.