When a major workplace incident occurs, it is easy to focus on the immediate cause—a failed piece of equipment, a worker’s mistake or an unexpected sequence of events. However, time and again, investigations reveal that catastrophic incidents are rarely caused by a single failure. Instead, they are often the result of multiple weaknesses aligning to create the conditions for disaster.
Whether examining a construction fatality, chemical release, mine collapse or transportation accident, the same themes continue to emerge. Here are five of the most common failures identified in fatal workplace investigations around the world.
1. Inadequate Risk Assessment
Many fatal incidents occur because hazards were not properly identified or the risks were underestimated before work began. Effective risk assessments should consider not only routine operations but also non-routine tasks such as maintenance, shutdowns and emergency work.
For example, the 2019 Whakaari (White Island) volcanic eruption in New Zealand, which killed 22 people including tour guides and workers, demonstrated the consequences of underestimating low-probability but high-consequence hazards. Subsequent investigations found that although volcanic activity and associated risks were known, the assessment and management of those risks were inadequate for the conditions at the time. The case illustrates the importance of continually reviewing risk assessments, considering changing conditions and ensuring that critical decisions are based on the latest available information rather than historical experience.
2. Weak Management of Change
Changes to equipment, personnel, processes or operating conditions often introduce new hazards. Unfortunately, organisations sometimes fail to formally assess the safety implications of those changes.
Historical investigations, including the Deepwater Horizon disaster, have shown how late operational changes, evolving work plans and inadequate evaluation of altered conditions contributed to the loss of control of critical systems. Effective management of change processes help ensure that modifications are properly reviewed, communicated and controlled before implementation.
3. Failure of Critical Controls
Fatal incidents frequently occur not because hazards are unknown, but because the barriers intended to prevent or mitigate them are absent, ineffective or bypassed.
Examples include inadequate machine guarding, missing fall protection, failed isolation procedures or poorly maintained safety systems. Investigations into major industrial accidents consistently emphasise that organisations should identify their critical controls and verify that they remain effective throughout the lifecycle of an operation. Simply assuming that safeguards are in place is rarely sufficient.
The 2019 Philadelphia Energy Solutions refinery explosion provides a powerful example. Investigators found that a corroded pipe elbow ruptured, releasing a flammable hydrocarbon vapour cloud that ignited and triggered multiple explosions. While operators successfully activated one emergency system to rapidly remove hydrofluoric acid from the process, other critical safeguards—including water suppression systems intended to reduce airborne hydrofluoric acid—failed to operate as designed after losing power. The incident demonstrated how degradation of equipment and failures in safety-critical systems can significantly increase the severity of an event and highlighted the importance of maintaining, testing and independently verifying critical controls throughout the life of an asset.
4. Poor Communication and Safety Culture
Many major incidents are preceded by warning signs that were recognised by workers but not effectively communicated, escalated or acted upon. A healthy safety culture encourages employees to report concerns, challenge decisions and stop work when necessary without fear of criticism or retaliation. Conversely, weak communication channels and a culture that prioritises production or commercial objectives over safety can allow risks to accumulate unnoticed.
Reviews of major disasters across multiple industries—including aviation, energy and manufacturing—have repeatedly highlighted cultural issues, ineffective communication and reluctance to challenge unsafe decisions as underlying contributors. Strong safety cultures encourage workers to speak up, report hazards and stop work when conditions become unsafe.
The Boeing 737 MAX crisis, which resulted in two fatal crashes and the loss of 346 lives in 2018 and 2019, is widely regarded as an example of how organisational culture and communication failures can contribute to catastrophic outcomes. Subsequent reviews identified shortcomings in safety communication, inconsistent reporting processes and a disconnect between leadership and frontline employees regarding safety concerns. Internal messages and later investigations highlighted concerns that safety issues were not always effectively escalated or addressed, reinforcing the importance of transparent reporting systems, psychological safety and leadership commitment to prioritising safety above competing pressures.
5. Inadequate Supervision, Competence and Planning
Even experienced workers require appropriate supervision, clear procedures and sufficient training for the tasks they perform. Fatal investigations often reveal gaps in competency management, particularly during contractor activities, maintenance work and high-risk non-routine operations.
One of the strongest examples for illustrating inadequate supervision, competence and planning is the 2020 Beirut Port explosion. While the disaster had many contributing factors, multiple investigations concluded that years of poor oversight, inadequate governance, weak planning and failures to act on known risks played a central role.
Whether involving confined spaces, excavations, lifting operations or chemical handling, inadequate planning and insufficient oversight continue to feature prominently in investigation reports. Organisations that invest in competency assurance and thorough pre-task planning are better positioned to prevent incidents before they occur.
The Common Thread
Perhaps the most important lesson from major investigations is that catastrophic events are seldom caused by a single error. More often, they result from multiple organisational weaknesses aligning at the wrong time. Equipment failures, human mistakes and environmental conditions may trigger an incident, but deeper issues—such as ineffective risk management, poor planning or weak governance—often determine whether that incident becomes a tragedy.
For health and safety professionals, the challenge is not simply to investigate failures after they occur but to identify and strengthen these underlying systems before an accident happens.
A Question for Your Organisation
If a serious incident occurred in your workplace tomorrow, would the investigation uncover the same recurring themes seen in so many major disasters—or could you confidently demonstrate that your risk assessments, management of change processes, critical controls, supervision and safety culture are robust enough to prevent them?
The best organisations don’t wait for an investigation to reveal their weaknesses—they actively look for them every day.
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