Classification
- Incident Type: Allision
- Severity: High
- Tug involvement: yes
- Tug mechanism: Assist tugs were used during undocking; one was released before the maneuver was complete.
Vessel Details
| Field | Value |
|---|---|
| Vessel Name | American Liberty |
| Vessel Type | Tanker (product tanker) |
| Flag State | United States [US] |
| IMO Number | 9763851 |
| Gross Tonnage | 29,801 |
| LOA (m) | 183.3 |
| Breadth (m) | 32.2 |
| TEU | N/A |
| Year Built | 2017 |
| Crew Size | 23 |
Incident Details
| Field | Value |
|---|---|
| Date | 2019-05-16 |
| Location | Lower Mississippi River, mile 139.5 near Reserve, Louisiana |
| Coordinates | 30.053167, -90.583000 |
| Region | United States |
| Fatalities | |
| Injuries | 4 (1 serious, 3 minor) |
| Missing | |
| Outcome | American Liberty was secured with tug assistance, underwent temporary and permanent repairs, and no pollution was reported. |
| Direct Damage | |
| Estimated Economic Damage | USD 40,563,851 |
Key facts
- American Liberty was fully laden with low-sulfur diesel fuel and gasoline and was preparing to leave Marathon Petroleum Garyville Dock No. 2 for Tampa Bay.
- The Mississippi River was at major flood stage, with the Baton Rouge gage at 43.6 feet; the current was estimated at 4 to 5 knots in the NTSB account.
- The vessel contacted the Don D crane barge, Ever Grace, hopper barges, and terminal wharfs while drifting downriver. African Griffon was among the moored vessels in the contact sequence.
- Four stevedores sustained one serious and three minor injuries. No pollution was reported because the double hull prevented cargo tanks from being penetrated.
- Combined property damage to vessels, barges, and wharfs was USD 40,563,851. American Liberty was later drydocked for permanent hull repairs.
Narrative
The Mississippi River was at major flood stage on 16 May 2019, with the Baton Rouge gage reading 43.6 feet. American Liberty, a 601.3-foot US-flagged product tanker built in 2017, was fully laden with low-sulfur diesel fuel and gasoline for Tampa Bay. There were 23 crewmembers aboard, and a federal pilot joined the bridge before the undocking maneuver. The assisting tugs Josephine Anne and Vera Bisso were positioned for the planned turn downriver.
The pilot began undocking with the engine dead slow ahead and Josephine Anne pulling. Before the maneuver was complete, Vera Bisso was released. The pilot and master then used non-standard engine commands and did not maintain a shared understanding of the engine order telegraph. The master made several engine-order changes without informing the pilot, while the pilot and master also gave conflicting rudder orders. The vessel did not gain enough speed to maneuver against the strong downstream current.
At 2042 central daylight time, the port quarter of American Liberty struck the Don D crane barge. The vessel continued downriver and subsequently contacted Ever Grace, hopper barges, and terminal wharfs. VTS closed the river, and the tanker was secured at the PSL Upper Globalplex Reserve Wharf with assistance from three tugs. Four stevedores on African Griffon and Don D were injured, one seriously and three with minor injuries. No flooding or pollution was reported, and the double hull prevented penetration of the cargo tanks.
The NTSB found that the main engine responded as expected. It determined that poor bridge resource management and miscommunication between the pilot and master delayed execution of an engine order and the attainment of sufficient speed for the undocking maneuver. The decision to release the assisting tugs before the maneuver was complete contributed to the accident. American Liberty later underwent temporary repairs, was drydocked for permanent hull repairs, and returned to service.
Sequence of events
| Date/time | Event |
|---|---|
| 2019-05-16 19:55 CDT | The federal pilot came on the bridge before departure from Garyville. |
| 2019-05-16 20:28 CDT | Undocking began with Josephine Anne assisting on the port bow. |
| 2019-05-16 20:34 CDT | Vera Bisso was released before the undocking maneuver was complete. |
| 2019-05-16 20:42 CDT | American Liberty contacted the Don D crane barge. |
| 2019-05-16 20:45 CDT | The tanker contacted Ever Grace. |
| 2019-05-16 20:51 CDT | The tanker contacted moored hopper barges. |
| 2019-05-17 01:42 CDT | American Liberty was securely moored at PSL Upper Globalplex Reserve Wharf. |
Contributing factors
| Factor | Evidence status | Description |
|---|---|---|
| Poor bridge resource management | Confirmed finding | The NTSB identified poor bridge resource management as part of the probable cause. |
| Miscommunication between pilot and master | Confirmed finding | Non-standard orders, delayed execution, undisclosed engine-order changes, and conflicting command strategies prevented a shared understanding on the bridge. |
| Premature release of assisting tug | Confirmed finding | The assisting tug was released before the undocking maneuver was complete in high river conditions. |
| High river conditions | Confirmed finding | Flood-stage conditions and a strong downstream current reduced the vessel's ability to gain maneuvering speed. |
| Main engine performance | Confirmed finding | NTSB analysis found that the main engine responded as expected and did not identify an engine malfunction as the cause. |
Investigation
The National Transportation Safety Board investigated the contact as Marine Accident Brief NTSB/MAB-20/39, accident DCA19FM034. The report documented the undocking sequence, bridge communications, tug use, contacts, injuries, damage, and engine-performance analysis. Its probable-cause finding was poor bridge resource management and miscommunication between the pilot and master, with premature release of the assisting tugs as a contributing factor.
References
- NTSB source note
- NTSB Marine Accident Brief NTSB/MAB-20/39