Modern U.S. colonels usually command Army infantry, artillery, armor, aviation or other types of brigades, USMC regiments, Marine Expeditionary Units or Marine Aircraft Groups, and USAF groups or wings. An Army colonel typically commands brigade-sized units (4,000 to 6,000 soldiers), with another colonel or a lieutenant colonel as deputy commander, a major as executive officer, and a command sergeant major as a senior non-commissioned officer (NCO) advisor. An Air Force colonel typically commands a wing consisting of 1,000 to 4,000+ airmen with another colonel as the vice commander and a Chief Master Sergeant (a “Command Chief”) as principal senior NCO enlisted adviser. Some USAF colonels are commanders of groups, which are the major components of wings. Colonels are also found as the chief of staff at divisional level-(Army) or Numbered Air Force-level staff agencies.