Flight sergeant is a senior non-commissioned rank in the Royal Air Force and several other air forces which have adopted all or part of the RAF rank structure. It is equivalent to a staff sergeant or colour sergeant in the British Army, a colour sergeant in the Royal Marines, and a chief petty officer in the Royal Navy, and has a NATO rank code of OR-7. In the RAF, flight sergeant ranks above chief technician and below warrant officer.

A non-commissioned officer (NCO) is a military officer who does not hold a commission. Non-commissioned officers usually earn their position of authority by promotion through the enlisted ranks. In contrast, commissioned officers usually enter directly from a military academy, officer training corps (OTC) or reserve officer training corps (ROTC), or officer candidate school (OCS) or officer training school (OTS), after receiving a post-secondary degree.