Major incidents place extraordinary demands on health systems and frontline clinical teams. They are characterised by sudden surges in patient numbers, complex logistics, and intense pressure to make rapid, high-consequence decisions. Emergency Departments (EDs) are at the centre of the hospital response, often acting as both the clinical and operational hub for the first few critical hours.

The United Kingdom has experienced several high-profile major incidents in recent years, including terrorist attacks, fires, transport disasters and mass casualty events. Each of these has generated detailed inquiries and governance reports, offering valuable insights into both strengths and shortcomings of existing systems. Alongside these real-world experiences, evolving guidance from RCEM and national triage developments such as the introduction of the Major Incident Triage Tool (MITT) provide ED teams with a clear mandate to prepare, adapt and improve.

This article synthesises evidence from national surveys, published literature and professional guidance to outline practical lessons for ED teams preparing for major incidents.

1. Preparedness Gaps Are Widely Acknowledged

A national survey of type-1 Emergency Departments in England found that confidence in major incident preparedness remains low. Many departments reported that they would struggle to mount and sustain an organised response in the context of existing crowding and staffing pressures. The survey also highlighted gaps in training, simulation frequency and the integration of major incident planning into day-to-day operational practice.

This is a critical finding. Major incidents do not occur in ideal circumstances; they happen in real hospitals already under strain. An over-reliance on paper plans or policy documents without testing in realistic conditions leaves departments vulnerable to disorganisation at the moment of greatest need (James et al., 2025).

Departments must view preparedness as an ongoing, iterative process that is embedded in daily culture rather than an occasional compliance exercise.

2. Plans Must Be Structured, Flexible and Regularly Rehearsed

A major incident plan should not be a static document. RCEM guidance stresses the importance of well-structured, functionally organised plans that can scale according to incident size and complexity. Roles should be allocated by function rather than named individuals to allow flexibility when staffing changes.

Plans should outline:

• Command and control structure at departmental, hospital and regional levels

• Activation criteria and escalation triggers

• Triage and patient flow processes including re-triage of existing patients

• Communication pathways both internal and external

• Welfare arrangements for staff

• Links with external partners, including ambulance services and other receiving hospitals

Regular rehearsals are critical. Table-top exercises, live simulations and multi-agency drills enable teams to understand their roles and highlight gaps that cannot be identified through policy review alone (Royal College of Emergency Medicine, n.d.-a; Royal College of Emergency Medicine, n.d.-b).

The key is adaptability. Plans should function for a small surge event as well as a large mass casualty scenario, without creating parallel, disjointed systems.

3. Leadership and Command Structures Must Be Unambiguous

Leadership failures are repeatedly identified in post-incident reviews. Confusion about who holds command, overlapping responsibilities and delayed decision-making can undermine even well-designed plans.

A clear Incident Command Structure, aligned with the hospital’s tactical and strategic command, is essential. Senior ED clinicians must know whether they are leading the clinical response at the front door or participating in higher-level tactical decision-making. Roles should be visible and easily identifiable, and escalation pathways should be rehearsed in advance.

Action cards, role badges and predefined reporting hierarchies provide structure during periods of cognitive overload. Leadership should also include designated communication leads and clinical coordinators to allow the senior decision-maker to focus on strategic direction.

4. Triage Is the Clinical Foundation of Effective Response

Triage is a critical clinical task during major incidents. It determines how limited resources are allocated and ultimately affects mortality and morbidity. Historically, the NASMeD Sieve and Triage Sort were used in the UK, but evidence has demonstrated poor sensitivity for identifying patients who require life-saving interventions.

In 2022, Vassallo and colleagues introduced the Major Incident Triage Tool (MITT), designed to replace older systems. MITT simplifies triage, unifies adult and paediatric pathways, and incorporates physiologically derived thresholds based on logistic regression modelling. It uses respiratory rate and heart rate criteria to identify high-risk patients and automatically assigns Priority 1 to children under two years. Importantly, MITT eliminates the “minimal” category at the initial triage stage, preventing occult injuries from being overlooked.

ED teams must train to use MITT confidently. During a major incident, patients already in the department should be re-triaged to align with the incoming patient stream. Regular exercises and drills incorporating MITT will ensure that staff can apply the tool instinctively under pressure (Vassallo et al., 2022).

5. Communication Systems Require Deliberate Planning

Communication failures are among the most frequently cited problems in post-incident analyses. Overloaded radio networks, contradictory messages and fragmented situational awareness can severely impair coordination.

EDs should designate a communication officer early in the response, establish structured briefing intervals, and maintain a central situation board or dashboard. Agreed terminology should be used consistently to avoid misinterpretation between teams. Communication systems should be tested during exercises to identify vulnerabilities in equipment, signal coverage or staff familiarity.

6. Surge Capacity Extends Beyond Physical Space

Many surge plans focus on creating more physical cubicles, but real-world experience shows that diagnostic bottlenecks, blood products, IT systems and documentation are often the true limiting factors. Pre-prepared packs, standardised request forms, and clearly defined escalation pathways for imaging and laboratory services can significantly reduce delays.

ED surge planning must consider the entire patient journey. This includes identifying holding areas for minor injuries, ensuring rapid transfer to theatre and critical care for Priority 1 patients, and planning efficient discharge routes for those who do not require admission.

7. Staff Welfare and Psychological Safety Are Core Operational Needs

Major incidents are emotionally and physically demanding. Prolonged shifts, exposure to traumatic injuries and high cognitive load can have lasting effects on staff wellbeing. Hot debriefs (immediate) and cold debriefs (structured follow-up) are essential for both operational learning and psychological processing.

Providing welfare areas, refreshments and opportunities for rotation can prevent fatigue-related errors. Embedding psychological support services as part of the major incident plan improves both immediate performance and long-term staff retention.

8. Governance, Simulation and Feedback Close the Learning Cycle

Preparedness is not a one-off event. Regular simulation and structured debriefing, integrated into governance cycles, enable continuous improvement. Post-incident reviews should focus on identifying system-level issues and implementing concrete changes.

Audit data should include time to triage, time to critical intervention, communication failures, and staff feedback. Lessons learned should feed into updated policies, training programmes and future exercises. This governance cycle ensures that learning from one incident strengthens future responses.

Conclusion

Major incidents are inevitable, but disorganisation is not. By learning from real events, embracing evidence-based triage, clarifying leadership structures, strengthening communication, planning realistic surge capacity, supporting staff welfare and embedding governance, ED teams can deliver safer, more coordinated and more resilient responses.

Preparedness must be active, multidisciplinary and continuous. The evolution of national guidance and triage tools provides EDs with the structure and evidence needed to transform plans into operational readiness. The time to prepare is now, not when the next siren sounds.

References

James, L., Armstrong, S., Beadman, M., Blackwell, R., Borakati, A., Bouamra, O., Coats, T., Griffiths, S., Hamilton, F., Metcalfe, J., Page, T., Patel, J., Price, C., & Martin, M. (2025). Preparedness for major incidents in Emergency Departments in England: A national cross-sectional survey. Emergency Medicine Journal, 42(7), 418–424. https://doi.org/10.1136/emermed-2024-213279 

Royal College of Emergency Medicine. (n.d.-a). Major incidents 2: Incident plans. RCEMLearning. Retrieved October 8, 2025, from https://www.rcemlearning.co.uk/foamed/major-incidents-2-incident-plans/ 

Royal College of Emergency Medicine. (n.d.-b). T2 Major Incident Management. RCEMLearning. Retrieved October 8, 2025, from https://www.rcemlearning.org/wp-content/uploads/T2-Major-Incident-Management.pdf 

Vassallo, J., Moran, C. G., Cowburn, P., & Smith, J. E. (2022). New NHS Prehospital Major Incident Triage Tool: from MIMMS to MITT. Emergency Medicine Journal, 39(11), 800–802. https://doi.org/10.1136/emermed-2022-212569