Army calls them Mr. or called pilots Mr. To make a long story short except for training, I didn't spend much of my enlistment where officers were saluted.
Yeah, E-3 down was Mr.,E-4 up called them "chief" in the amphibs and with way more respect than ensigns we called sir.
Marines make it simple.. Everybody not enlisted including all officers, warrant officers and civilian employees are to be called sir... Enlisted men are not to be called sir. They work for a living Ohhh-Rahhh...
Our ancestors made it simpler still, " listen up! See that guy dressed like a barber pole? That is the head good guy, do whatever he says. See that guy on the other side dressed in pokadots? That is the bad guy KILL HIM! Got it? any questions? YOU! Turn that helmet around, unless your nose is in the back? Archers? POINTY ENDS OUT!, and shoot early and often! "
Army Warrants are called Mr at least they were in aviation (helicopter) units during Vn. I know very little about the AF, Marines or Navy as I never served in them. In today's Army, another use for the WO is a promotion path for NCOs in Special Forces. I do not know if that applies in RA or Regular Army.
IIRC (and I may not, 40 years ago) Warrant pilots were (are?) unique to the Army, and didn't follow the usual enlisted path back in them thar days. The Army needed pilots and opened the path to fly from enlisted ranks starting in basic, wash out of flight school and back to grunt status. To my (limited) knowledge, the Navy didn't do that at all. Warrant was a path to commissioning, but only as a Limited Duty Officer ( not a line officer, so could not be in command of a major vessel) and IIRC (again) maxed out as LCDR (O4.)
