Confidential Human Factors
Incident Reporting Programme
The Charity
Aviation
Maritime
M2715
Initial Report
While the vessel was adrift, a tender was being prepared for towing from the swimming platform. The line was connected and, following communication between deck and bridge, the operation proceeded on the understanding that it was correctly rigged. As the vessel moved ahead, tension built in the line, which then fouled on the upper section of a bitt, creating a restriction under load.
The officer approached to clear it and, with the line still under tension, attempted to free it by kicking it. When the line suddenly released, it recoiled violently, striking the officer on the arm and neck and briefly rendering them unconscious.
First aid was provided on board, and the casualty was taken ashore for assessment. No serious injuries were found, and they returned to the vessel later the same day.
The operation proceeded on the assumption that the line was correctly set. The fouling under load, combined with attempts to intervene without first removing tension, increased the risk. This highlights the dangers of working on tensioned lines and the need to pause and make the situation safe before acting.
CHIRP Comment
This report details a serious incident involving a tensioned line, a known high‑risk hazard in maritime operations. The events suggest that the towing operation proceeded on the assumption that the line was correctly rigged, without a final check once the vessel began to move ahead. As the load was applied, the line fouled on the bitt, and an unsafe condition developed that was not immediately recognised. A key learning point is the attempt to intervene while the line remained under tension. Attempting to free a loaded line exposes crew members to the risk of sudden release and snapback, which can result in serious injury or fatality. The importance of identifying and clearly understanding snap‑back zones must be emphasised, as these areas present a well‑documented and potentially fatal risk when
lines fail or release under load. Although an injury occurred, the consequences could have been significantly more severe.
This incident highlights the importance of treating all tensioned lines as high‑risk, avoiding assumptions by using positive verification before any load is applied, and halting operations to remove tension before any intervention. Effective communication between the bridge and deck teams remains essential throughout such operations. There is also a recognised lack of accessible guidance and information on yacht towing operations involving tenders and on-tow line‑handling practices more generally. This gap may contribute to an inconsistent understanding of associated hazards, including the risks posed by tensioned lines and snap-back zones.
Supervision is another important factor. While it is acknowledged that crew resources can be limited, there remains a clear responsibility to ensure appropriate supervision during operations. Distractions that reduce the effectiveness of supervisory oversight should be avoided, as they can contribute to unsafe situations developing or to them not being identified in time. A stop-work authority action is a suitable safeguard if the companies that train their staff to use it feel they have the necessary confidence and empowerment to do so.
This near miss serves as a reminder of how quickly routine tasks can escalate when stored energy is involved, and of the importance of pausing to reassess and ensure the situation is safe before acting.
Key Issues relating to this report
Factors related to this report
Complacency – is evident in the assumption that the towing line was correctly rigged without a positive verification once the load was applied. The operation appears to have been treated as routine, reducing vigilance at a critical moment.
Situational Awareness – is reflected in the failure to fully recognise the hazard posed by a tensioned and fouled line, particularly the risks associated with stored energy and snapback zones.
Communication – may have contributed, as although there was contact between bridge and deck, there is no indication that a shared mental model of the developing hazard (fouling under load) was established.
Teamwork/Assertiveness – is suggested by the absence of challenge or pause before intervention, with no evidence of cross-checking or escalation before attempting to clear the line.
Capability (or insufficient application of training) is indicated in the choice to physically intervene on a tensioned line, contrary to widely taught safe line-handling practices.
Key Takeaways
Regulators – Known risks are not the same as managed risks. This case emphasises that well-known hazards such as snapback and stored energy persist despite extensive guidance, suggesting that current safety messages are not consistently influencing operational behaviour. There is an opportunity to better embed, assess, and reinforce guidance such as MGN 520 across the industry, particularly regarding dynamic risk assessment and interventions.
Managers (Company / Operators) – Procedures only protect people when they shape real behaviour on deck. The incident indicates a gap between procedures and practice, especially in stopping work when conditions deviate from the plan. Managers should consider how effectively crews are trained and empowered to pause operations, how clearly snapback risks are demonstrated, and whether supervision and onboard culture actively reinforce conservative decision-making in routine tasks.
For Seafarers – If it’s under load, don’t touch it; make it safe first. This event is a reminder that tensioned lines are inherently dangerous and can become lethal without warning. Intervening before removing the load, even with simple actions, can lead to serious consequences. Taking a moment to stop, reassess, and make the situation safe is always the safer option, even under perceived pressure to continue.