399th explained

399th may refer to:

• 399th Bombardment Group, inactive United States Air Force unit
• 399th Bombardment Squadron or 99th Air Refueling Squadron, part of the 6th Air Mobility Wing at Birmingham Air National Guard Base, Alabama
• 399th Fighter Squadron or 57th Weather Reconnaissance Squadron, inactive United States Air Force Reserve squadron

See also

• 399 (number)
• 399, the year 399 (CCCXCIX) of the Julian calendar
• 399 BC