It's interesting that the Army is the only branch that uses warrants for pilot duty. Most Army helicopter pilots are warrants. By law, a commissioned officer has to pilot manned military aircraft. Warrants are commissioned officers, technically, as I understand it, they are commissioned by congress, and not the president. We had this term... RCO's. They were 'Regular Commissioned Officers' to differentiate them from warrants, which would predominate flight squadrons and motorpool maintenance, etc. when you had a large pool of warrants mixed in with normal officers.