Degraded mode in workplace safety: why address it before a task ?
It is essential to address degraded mode before starting a task in order to identify the real risks and implement appropriate preventive measures. This helps prevent workplace accidents by aligning the team around an accurate risk analysis.
What is a degraded mode in safety ?
A degraded mode refers to a situation in which one or more safety barriers, whether technical, human, or organizational, lose effectiveness, thereby increasing the actual level of risk. In high risk industries, this often occurs during maintenance, shutdowns, or machine interventions, where improvisation can lead to dangerous workarounds. INRS (ED 134) emphasizes that safety is better managed during nominal production than during degraded modes, which are classic blind spots.
What are the risks of a degraded mode ?
Modern risk management approaches, such as the Swiss Cheese model, compare safety barriers to slices of cheese with holes: an accident occurs when the holes align. In degraded mode, these holes widen, making detection and compensation before the activity essential, through tools such as bow tie analysis or root cause analysis. Addressing this before the task helps align the team with the real level of risk and prevents a distorted perception of danger.
Why discuss it before starting a task ?
INRS recommends a specific risk assessment for interventions carried out in degraded mode, where protections are partially neutralized, increasing the likelihood of accidents outside normal production. The ARIA accident reports confirm that a degraded situation is often a “first step” toward an accident if it is not requalified, as seen in cases of tank overflows or normalized alarm bypasses. In a safety training session or safety day, integrating this discussion frames necessary adaptations and helps prevent workplace accidents.
Degraded mode and risk management models
The literature on High Reliability Organizations and resilience considers deviations as critical signals that must be collectively acknowledged. The normalization of deviance, theorized by Diane Vaughan, makes risky practices appear “acceptable” through habit, until the fatal alignment of weaknesses occurs. Discussing degraded mode before the task breaks this routine, strengthens shared vigilance, and reinforces the company’s safety culture.
How can degraded mode be integrated into your HSE practices ?
Addressing degraded mode upstream makes it possible to identify failing barriers, define compensatory measures and stop thresholds, avoid improvisation, and reclassify deviations as major risks within formal frameworks such as the risk assessment document and prevention plans. This integrates seamlessly into HSE or QHSE training, as well as behavioral safety visits such as BBS or VCS, supporting quality of work life and psychosocial risk prevention.
Briefing sentence:
“Before starting the task, let’s align on the real level of risk: which barriers are degraded? What compensations are in place? At what threshold do we stop? Without discussion, we remain in ‘nominal’ mode on a weakened system.”
Conclusion
Adopt the THINK BEFORE ACTING LMRA workshop to train your teams to anticipate degraded modes through rigorous risk analysis, ideal for safety days or workplace safety training. Our tailored support, including management coaching, formal risk assessment documentation, and HSE or QHSE training, strengthens your prevention culture, from behavioral safety visits to quality of work life modules, aiming for zero industrial accidents and optimal workplace well being.
Key Takeaways
- Degraded barriers mean increased real risk: detect and compensate before action, based on Swiss Cheese and barrier management principles.
- INRS and ARIA stress that degraded modes are blind spots that favor accidents outside nominal production.
- Avoid routine: prior discussion prevents normalization of deviance and strengthens organizational resilience.
- HSE practice: integrate into safety days, QHSE training, or behavioral safety visits to reinforce safety culture.
FAQ
What is a degraded mode?
It is a situation in which safety barriers, whether technical, human, or organizational, lose effectiveness, increasing the risk of workplace accidents, for example during maintenance or machine shutdown.
Why discuss it before the task?
To identify weaknesses, define compensations, and avoid improvisation or normalization of deviance, aligning the team with the real level of risk through a proper risk assessment.
What are the specific risks?
Improvised interventions, bypassing of machine safety systems, or alignment of weaknesses described by the Swiss Cheese model, often highlighted by INRS in HSE safety training.
How can a degraded mode be compensated?
Through clear stop thresholds, shared vigilance through behavioral safety practices, and a structured prevention plan that includes root cause analysis and occupational risk assessment.
Sources :
INRS. (s.d.). Intervenir sur un équipement de travail : penser sécurité (ED 134). https://www.inrs.fr/dam/inrs/CataloguePapier/ED/TI-ED-134.pdf
Griphe Conseil. (2022, 8 octobre). Sécurité au travail et mode dégradé. https://blog.griphe-conseil.fr/2012/07/securite-au-travail-et-mode-degrade-107698112/
The Decision Lab. (2023, 30 août). Modèle du fromage suisse. https://thedecisionlab.com/fr/reference-guide/management/swiss-cheese-model
Vaughan, D. (2010). The normalization of deviance. In Encyclopedia of Criminological Theory. SAGE Knowledge. https://sk.sagepub.com/ency/edvol/criminologicaltheory/chpt/vaughan-diane-normalization-deviance
ORSYS. (2025, 12 février). Définition Mode dégradé (fail-safe mode). https://www.orsys.fr/orsys-lemag/Glossaire/mode-degrade-fail-safe-mode/
BFU. (s.d.). Swiss cheese model – Atelier de prévention [PDF]. https://www.bfu.ch/media/p11cq0sd/2025_factsheet_swiss_cheese_model_fr.pdf
INERIS. (s.d.). Fiches ARIA : Accidents en maintenance/mode dégradé. Recherche sur ineris.fr (ex. : débordement cuves, shunts alarmes).