49 U.S.C. § 1131

(a) General .— (1) The National Transportation Safety Board shall investigate or have investigated (in detail the Board prescribes) and establish the facts, circumstances, and cause or probable cause of— (A) an aircraft accident the Board has authority to investigate under section 1132 of this title or an aircraft accident involving a public aircraft as defined by section 40102(a) of this title other than an aircraft operated by the Armed Forces or by an intelligence agency of the United States; (B) a highway accident, including a railroad grade crossing accident, the Board selects, concurrent with any State investigation, in which case the Board and the relevant State agencies shall coordinate to ensure both the Board and State agencies have timely access to the information needed to conduct each such investigation, including any criminal and enforcement activities conducted by the relevant State agency; (C) a railroad— (i) accident in which there is a fatality or substantial property damage, except— (I) a grade crossing accident or incident, unless selected by the Board; or (II) an accident or incident involving a trespasser, unless selected by the Board; or (ii) accident or incident that involves a passenger train, except in any case in which such accident or incident resulted in no fatalities or serious injuries to the passengers or crewmembers of such train, and— (I) was a grade crossing accident or incident, unless selected by the Board; or (II) such accident or incident involved a trespasser, unless selected by the Board; (D) a pipeline accident in which there is a fatality, substantial property damage, or significant injury to the environment; (E) a major marine casualty (except a casualty involving only public vessels) occurring on or under the navigable waters, internal waters, or the territorial sea of the United States as described in Presidential Proclamation No. 5928 of December 27, 1988 , or involving a vessel of the United States (as defined in section 116 of title 46 ), under regulations prescribed jointly by the Board and the head of the department in which the Coast Guard is operating; and (F) any other accident related to the transportation of individuals or property when the Board decides— (i) the accident is catastrophic; (ii) the accident involves problems of a recurring character; or (iii) the investigation of the accident would carry out this chapter. (2) (A) Subject to the requirements of this paragraph, an investigation by the Board under paragraph (1)(A)–(D) or (F) of this subsection has priority over any investigation by another department, agency, or instrumentality of the United States Government. The Board shall provide for appropriate participation by other departments, agencies, or instrumentalities in the investigation. However, those departments, agencies, or instrumentalities may not participate in the decision of the Board about the probable cause of the accident. (B) If the Attorney General, in consultation with the Chairman of the Board, determines and notifies the Board that circumstances reasonably indicate that the accident may have been caused by an intentional criminal act, the Board shall relinquish investigative priority to the Federal Bureau of Investigation. The relinquishment of investigative priority by the Board shall not otherwise affect the authority of the Board to continue its investigation under this section. (C) If a Federal law enforcement agency suspects and notifies the Board that an accident being investigated by the Board under subparagraph (A), (B), (C), or (D) of paragraph (1) may have been caused by an intentional criminal act, the Board, in consultation with the law enforcement agency, shall take necessary actions to ensure that evidence of the criminal act is preserved. (3) This section and sections 1113, 1116(b), 1133, and 1134(a) and (c)–(e) of this title do not affect the authority of another department, agency, or instrumentality of the Government to investigate an accident under applicable law or to obtain information directly from the parties involved in, and witnesses to, the accident. The Board and other departments, agencies, and instrumentalities shall ensure that appropriate information developed about the accident is exchanged in a timely manner. (b) Accidents Involving Public Vessels .— (1) The Board or the head of the department in which the Coast Guard is operating shall investigate and establish the facts, circumstances, and cause or probable cause of a marine accident involving a public vessel and any other vessel. The results of the investigation shall be made available to the public. (2) Paragraph (1) of this subsection and subsection (a)(1)(E) of this section do not affect the responsibility, under another law of the United States, of the head of the department in which the Coast Guard is operating. (c) Accidents Not Involving Government Misfeasance or Nonfeasance .— (1) When asked by the Board, the Secretary of Transportation or the Secretary of the department in which the Coast Guard is operating may— (A) investigate an accident described under subsection (a) or (b) of this section in which misfeasance or nonfeasance by the Government has not been alleged; and (B) report the facts and circumstances of the accident to the Board. (2) The Board shall use the report in establishing cause or probable cause of an accident described under subsection (a) or (b) of this section. (d) Accidents Involving Public Aircraft .— The Board, in furtherance of its investigative duties with respect to public aircraft accidents under subsection (a)(1)(A) of this section, shall have the same duties and powers as are specified for civil aircraft accidents under sections 1132(a), 1132(b), and 1134(a), (b), (d), and (f) of this title. (e) Accident Reports .— The Board shall report on the facts and circumstances of each accident investigated by it under subsection (a) or (b) of this section. The Board shall make each report available to the public— (1) in electronic form at no cost in a publicly accessible database on a website of the Board; and (2) if the electronic form required in paragraph (1) is not printable, in printed form upon a reasonable request at a reasonable cost. (f) Timeliness of Reports .— If any accident report under subsection (e) is not completed within 2 years from the date of the accident, the Board shall submit to the Committee on Transportation and Infrastructure of the House of Representatives and the Committee on Commerce, Science, and Transportation of the Senate a report identifying such accident report and the reasons for which such report has not been completed. The Board shall report progress toward completion of the accident report to each such Committees every 90 days thereafter, until such time as the accident report is completed.