Limited duty officer

A limited duty officer (LDO) is an officer in the United States Navy or United States Marine Corps who was selected for commissioning based on skill and expertise, and is not required to have a bachelor's degree. They are employed in situations where it is desirable to have an officer with strong, specific technical knowledge and seasoned leadership. Per Title 10, U.S. Code, an LDO is a permanent commissioned officer appointed under section 5589 in a permanent grade above chief warrant officer, W-5, and designated for limited duty.

LDOs do not attend a conventional pre-commissioning program such as a twelve-to-fourteen week Officer Candidate School program. Instead, they typically attend a four-to-five week LDO/CWO indoctrination school as commissioned officers. In the U.S. Navy, this school was previously under the auspices of Naval Aviation Schools Command at NAS Pensacola, Florida. It is now known as the LDO/CWO Academy under the auspices of Officer Training Command at Naval Station Newport, Rhode Island.

LDOs perform similar tasks as those of warrant officer (WO), but the formal definition differences are subtle and focus on the degree of authority and level of responsibility, as well as the breadth of required expertise. The term "limited duty" refers not to an LDO's authority, but rather the LDO's career progression and restrictions. Historically an LDO, prior to World War II, could only advance as far as lieutenant (O-3E) in the Navy and captain (O-3E) in the Marine Corps. In later years, an LDO could be promoted to commander (O-5) and, in the Marine Corps, the senior LDO rank remains lieutenant colonel (O-5). In the 1990s, the ceiling in most U.S. Navy LDO communities was raised to captain (O-6).

The LDO/CWO motto is "sursum ab ordine" which means "up from the ranks" to underline a distinction between LDOs and CWOs and those Naval and Marine Corps officers commissioned directly from collegiate programs such as the United States Naval Academy, United States Merchant Marine Academy, Naval ROTC and Marine Corps Platoon Leaders Class, and similar post-collegiate pre-commissioning officer candidate programs of the Navy and Marine Corps such as Officer Candidate School and the since-disestablished Aviation Officer Candidate School.

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