49 CFR § 831.5 - Priority of NTSB investigations.
(a) Relationships with other agencies.
(1) Except as provided in 49 U.S.C. 1131(a)(2)(B) and (C) regarding suspected criminal actions, an investigation conducted under the authority of the NTSB has priority over any investigation conducted by another Federal agency.
(2) The NTSB will provide for appropriate participation by other Federal agencies in any NTSB investigation. Such agencies may not participate in the NTSB's probable cause determination.
(3) The NTSB has first right to access wreckage, information, and resources, and to interview witnesses the NTSB deems pertinent to its investigation.
(4) As indicated in § 831.9(c) of this part, the NTSB has exclusive authority to decide when and how the testing and examination of evidence will occur.
(5) The NTSB and other Federal agencies will exchange information obtained or developed about the accident in the course of their investigations in a timely manner. Nothing in this section prohibits the NTSB from sharing factual information with other agencies.
(6) Incident command system. The NTSB recognizes the role of incident command systems to address emergencies. The NTSB does not assume the role of a first responder agency.
(i) The NTSB IIC or his designee will participate in the incident command system to identify and coordinate investigative needs related to the preservation and collection of information and evidence.
(ii) The NTSB may collect information and evidence from the incident command in a timely and reasonable manner so as not to interfere with its operations.
(b) Investigations by other Federal agencies.
(1) Nothing in this section limits the authority of any Federal agency to conduct an investigation of an accident or incident under applicable provisions of law or to obtain information directly from parties involved in, and witnesses to, a transportation accident. Other agencies are expected to coordinate with the NTSB IIC to avoid interference with, and duplication of, the NTSB's investigative efforts. These agencies will not participate in the NTSB's probable cause determination.
(2) The NTSB recognizes that state and local agencies may conduct activities related to an accident under investigation by the NTSB. These agencies will not participate in the NTSB's probable cause determination.
(3) Except as described in § 831.30 of this part regarding highway investigations, the NTSB may request that a Federal agency provide to the NTSB the results of that agency's investigation of an accident when such investigation is intended to result in safety improvements or remedial action. The NTSB will not routinely request regulatory enforcement records or investigation results.