49 CFR §831.58

1. (a)In addition to the subpoena and deposition authority delegated to investigative officers under this chapter, a person designated as IIC for an investigation is authorized to—
   1. (1)Organize, conduct, control, and manage the field phase of an investigation, even when a Board Member is present.
   2. (2)Coordinate all resources and provide direction to all persons (including persons not employed by the NTSB) involved in an on-site investigation.
   3. (3)Work with other Federal agencies in the investigation of a marine casualty or major marine casualty when other agencies are participating, to ensure all agencies will obtain the information, evidence, and resources needed for the investigation(s) or investigative activities.
   4. (4)Work with the USCG to ensure the agencies do not duplicate work to the maximum extent practicable.
   5. (5)Continue his or her organizational and management responsibilities through all phases of the investigation, including consideration and adoption of a report or brief determining one or more probable causes of a marine casualty or major marine casualty.