---
kind: "section"
citation: "49 C.F.R. § 831.51"
title: "49"
number: "831.51"
heading: "Definitions."
url: "https://uscodex.org/cfr/49/831.51"
---

# §831.51. Definitions.


The following definitions apply throughout this subpart.

IIC means the NTSB investigator-in-charge.

Investigative activity means an activity performed by or under the direction of the NTSB during a casualty investigation led by the USCG.

Major marine casualty is defined in joint regulations of the NTSB and USCG at 49 CFR [850.5(e)](/cfr/49/850.5.md?p=e) and [46](/cfr/49/46.md) CFR 4.40-5(d), respectively.

Marine casualty means—

- (1) Any casualty, accident or event described in [46 CFR 4.03-1](/cfr/46/4.03-1.md)
- (2) An occurrence that results in an abandonment of a vessel
- (3) **Other marine occurrences that the NTSB or USCG, or both, determine require investigation.**

## Notes

### Authority

Authority: 49 U.S.C. 1113(f), 1116, 1131, 1134, unless otherwise noted.

### Source

Source: 82 FR 29694, June 29, 2017, unless otherwise noted.

### Authority

Authority: 49 U.S.C. 1113(f). Section 831.15 also issued under Pub. L. 101-410, 104 Stat. 890, amended by Pub. L. 114-74, sec. 701, 129 Stat. 584 (28 U.S.C. 2461 note).

### Source

Source: 82 FR 29685, June 29, 2017, unless otherwise noted.