What is the proper way to address NCOs in different branches?

Colonel, your response about calling Air Force personnel by their first name is an insult to every NCO and officer who ever donned a uniform. I don’t take your insult lightly, and, quite frankly, don’t give a dam what you did on active duty. I have no respect for any superior officer who, in any way, who disparages any enlisted person or junior officer. You are a disgrace to the uniform you wore.

I just say "what up dude/bro" seems to work

That’s because it’s boot camp everyone is address as sir or ma’am by recruits . Once out of boot camp the only officers are address as sir or ma’am

I've been told by a lot of higher ups, you should try and know the other branches rank system but if you don't sir or ma'am is the best way to address. Then that person may or may not clarify what rank they hold.

Being raised USAF everyone from E4 to E9 was Sgt. After being in the USN everyone from E4 to E6 was either Petty Officer or first/last name. E7 was Chief, E8 was Senior, E9 was Master Chief. CWO's and Mustangs was a whole different ball game, Sir was a safe bet.

No you don't call them sir. Only recruits call them sir because "there not Marines yet". An E-7 is addressed as Gunnery Sergeant or just Gunny if you know him and he is ok with you calling him/her that.
Staff Sergeant E-6 is called staff sergeant and not just sergeant. I'm army I learned that the hard way when I was an E-4.

Also it's good to know that as a Specialist you are not required to address there corporal's by there rank there the same rank as you. Also regulation state you will address someone who out ranks you by grade not rank. So don't ever let one of there corporal's push you around.

To this day after being out for awhile I still address the military by their rank. They have earned my respect

As to the response for the Air Force member addressing an NCO of another branch by their first name...I would have hemmed an Airman up if they addressed anyone other than sir or ma'am.

Sir yes sir...

This will be fun. I had the pleasure to work alongside the sister services while deployed to OIR (Op. Inherent Resolve) last year and you quickly pick up on the culture of the other branches. We called USMC Master Sergeants Top, Gunnery Sergeant's Gunny (Master Gunnery, Master Guns). All medical personnel were doc regardless of branch. Senior was just that. In the AF, the senior most NCO was simply senior. Varies by person to person and situation to situation but when using their rank, you can never go wrong.

Mostly called by rank, E3 and below by their last name, E4 and up by their rank unless they are Officers and the answer is yes Sir or no Sir. My men called me sarge others would say Sargent

In the army, E-1 through E-3 you can just call them by their name, E-4 has the lateral promotion so if the soldiers is a corporal you you call them corporal, if they are a specialist you dont have to call them by their rank u less they are a team leader. E-5 and up is just sergeant until you hit sergeant major, then you have officers which is just sir/ma'am.

I know in my unit it’s normal to call someone by their first name, as long as you out rank them and it’s within your work center. But technically, you should address people by their rank or abbreviations. Master Sergeant or Sergeant, Chief Master Sergeant or Chief, etc...

I’ve always called em all by their rank, the only one I throw a “sir or ma’am” to is officers..

When they are going through training, as you did, it's a whole different world. As an E4, you greet those of other branches with the same respect you deserve.

I ark have people calling me Sir!! I tell that just because you’re my sons-in-law, you don’t have to call me sir. Chief is good

While in training Boots call Their NCOs Sir
Or ma’am... only then.

As an Air Force SNCO I preferred Master Sgt. In today's joint environment it's an excellent question.

You are hearing NCO's being called sir/ma'am in boot camp so they get used to the word sir or ma'am. In the fleet, you call E-7 Chief.

If I addressed my PSG as Sergeant, with him actually being a SFC. Ain’t no damn way I’d disrespect him by calling a marine of the same rank something different. My PSG deserves all the respect in the world and if he was fine with Sergeant then a gunny would have to deal with it too...