Chief Master Sergeant (CMSgt) is the ninth enlisted rank in the UNSC Air Force, and is equal in pay-grade to Command Chief Master Sergeant and Chief Master Sergeant of the Air Force, and is above Senior Master Sergeant. The pay grade for Chief Master Sergeant is E-9, and is one of the highest ranks in the Senior Non-Commissioned Officer (SNCO) category in the UNSCAF.
Attaining the rank of Chief Master Sergeant is the pinnacle of an Air Force enlisted member's career. Some Chief Master Sergeants manage the efforts of all enlisted personnel within their unit or major subsection thereof, while others run major staff functions at higher headquarters levels. All Chief Master Sergeants are expected to serve as mentors for company-grade and field-grade commissioned officers, as well as non-commissioned officers and junior enlisted members, and to serve as advisers to unit commanders and senior officers.
Chief Master Sergeants are often referred to as "Chief."
The position of First Sergeant in the pay grade of E-9 is the highest rank in the United States Air Force that one can hold while serving in the special duty position of First Sergeant. They are senior enlisted advisers to a unit commander. These First Sergeants (pay grades E-7 to E-9) are referred to officially as "First Sergeant" (regardless of their pay grade), and unofficially as "First Shirt" or simply "Shirt" (though informal).