Flight sergeant is a term used in the military and is the highest non-commissioned rank in the Royal Air Force. Synonyms for flight sergeant could include senior NCO (non-commissioned officer), warrant officer or warrant officer class 2. Another synonym could be squadron leader, a commissioned officer who holds the rank of flight lieutenant or above. In the US Air Force, the term equivalent to flight sergeant is technical sergeant or TSgt. In other branches of the military, the equivalent might be staff sergeant, sergeant first class, or chief petty officer. These titles indicate the rank and responsibility level of the individual within the military hierarchy.