qnli question: What does junior NCO refer to in the USAF pay grade system? sentence: Above the pay grade of E-4 (i.e., pay grades E-5 through E-9) all ranks fall into the category of NCO and are further subdivided into "NCOs" (pay grades E-5 and E-6) and "Senior NCOs" (pay grades E-7 through E-9); the term "Junior NCO" is sometimes used to refer to staff sergeants and technical sergeants (pay grades E-5 and E-6).