When is calling a fellow service member by their first name acceptable and unacceptable?
Equal ranks yes, other ranks it depends on the situation and arena, and if it is initiated by them and what their guidance from seniors is in reference to it, main keys to looks at.
Typically it is not appropriate to become that familiar with each other because it takes the respect aspect somewhat out of the situation if something should change along the way from a personal conflict or disagreement. Then you run the risk of when it is deemed no longer from the senior and you are unknowing and you do it and they then try to pursue disrespect issues, it is safer and more appropriate even when they initiate it to respectfully decline and continue to address by rank and or position.
I tend to call my peers by their first name as well....but again, not around soldiers.
Sir, I came in the Military in 1984, and was raised by Vietnam Veterans. I understand that you come from the medical side of the house.
General Patton talks about the importance of maintaining military professionalism and being bottom line up front.
I do not feel comfortable with first names, and I understand that Senior Officers have a different protocol.
My insight is younger Officers, may not have an understanding that Senior Officers can call them by their first name, under regulation the direction is to call the Senior Officer by his rank.
I greatly appreciate your in-sight, and the 30 years I have in I prefer to maintain Military bearing at all times. It would be rather confusing to call the Chaplain my his or her first name.