<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (May 2010) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (May 2010) (Learn how and when to remove this template message) </Td> </Tr> <P> Senior Airman (SrA) is the fourth enlisted rank in the United States Air Force, just above Airman First Class and below Staff Sergeant . It has a pay grade of E-4 . Between its approval on 30 December 1975 (with implementation 1 June 1976) and 19 March 1991, Senior Airmen wore sleeve chevrons with blue center stars instead of silver to distinguish them from the non-commissioned officer rank of "Sergeant", also a pay grade of E-4 . The latter was abolished in 1991 and the blue center star was changed to white to conform to all enlisted rank chevrons . </P> <P> The Air Force promotes an Airman First Class (A1C) to Senior Airman after 36 months time in service (TIS) and 20 months time in grade (TIG), or 28 months TIG, whichever occurs first . Outstanding Airmen First Class, limited to no more than 15 percent of the total, may be promoted to Senior Airmen six months early, in a competitive process called Below - the - Zone, which normally involves going before a competitive board . Senior Airmen are expected to be technically proficient and begin to develop leadership skills, and may be expected to supervise an Airman of lesser rank . </P>

What does senior airman mean in the air force