202027 Compliant yet still 'fatigued'
Edited from TSB (Canada) official report M16P0378
A tug was pushing a barge in ballast. The tug was connected to the barge with pins; an arrangement commonly called an articulated tugbarge(ATB). At one point, the OOW altered the ATB’s course to port to
pass one nautical mile off an island at the entrance to a channel.
Just over 30 minutes later, the ATB passed the next port alteration waypoint off the island but did not alter course. At this time, the weather was light winds and rain, and a 0.3 metre sea. Another crew who was doing rounds called the OOW from the galley intercom radio but received no response. After a second attempt, again with no response, he made his way to the bridge. A few minutes later, while he was still on his way to the bridge, the ATB struck a known and charted reef at the entrance to the channel. Following the impact, the OOW reversed both engines and placed the rudders hard to port.
The noise of the engine in full reverse and/or the vibration of the tug alerted the remaining crew. The Master went to the upper wheelhouse, took over the watch, and instructed the OOW to ensure that the crew were awake and that they should survey the damage to the ATB. The tug’s starboard engine was disabled, so the Master attempted to reverse off the reef with the port engine and rudder. The ATB pivoted but did not move off the reef, and the tug made contact with the seabed several times. Because of damage to the tug, pollution occurred. The crew were forced to abandon ship and were recovered by local marine authorities.
Among others, the investigation found that the OOW had likely fallen asleep and missed executing the course alteration point. The OOW’s fatigue stemmed from two sources:
- Acute sleep disruption. He averaged 5.8 hours sleep on the three consecutive days preceding the accident instead of therecommended eight, and chronic sleep disruption. He had worked a very challenging and relentless schedule for the last 23 days. This disruption was further compounded by an individual factor: the OOW’s inability to nap on most days during the afternoon or early evening break.
- Additionally, as the OOW was alone on the bridge at night without a bridge navigation watchkeeping alarm system (BNWAS) or off-track alarms, there were no mitigating factors to prevent a sleep related occurrence from happening.
- This is a good example of why it is important to investigate for fatigue in an in-depth and fastidious manner. Even though the OOW may have been compliant with regulatory work-rest requirements, he was suffering from fatigue nonetheless;
- Alone on the bridge at night – not a best practice; The use of off-track alarms on ECDIS or ENCs is recommended; A BNWAS is another layer of safety that should be considered, even on vessels which are not required to carry this equipment due to their size.