Exercise Frostbite – A Mass Casualty Exercise at Hemel Snow Centre

In May, our team from Essex & Herts Air Ambulance took part in a large-scale, multi-agency training exercise at the Hemel Hempstead Snow Centre. Organised by East of England Ambulance Service and Hertfordshire Fire and Rescue Service, the scenario simulated a major road traffic collision in heavy snow conditions. The slope was closed to the public, and multiple vehicles were positioned on the snow with a combination of realistic manikins and live volunteers acting as patients.

The aim was to rehearse our joint response to a mass casualty incident in an incredibly challenging environment, and to test coordination between multiple emergency services including police, fire, ambulance, HEMS, Hazardous Area Response Team (HART), Lowland Rescue, and critical care charities.

Our Role

Our HEMS team was one of two critical care teams attending, working alongside our colleagues from the Beds & Herts Emergency Critical Care Scheme (BHECCS), with an advanced paramedic colleague designated as the critical care lead — taking responsibility for triaging the most seriously injured patients and coordinating critical care resources.

As a team comprising a doctor and a critical care paramedic, we were tasked with managing two patients. The first was in cardiac arrest and trapped between two vehicles. We performed initial advanced clinical interventions, supported the extrication effort alongside fire crews, and then handed care over to an advanced paramedic. We then treated a second patient with significant head and chest injuries, providing pre-hospital emergency anaesthesia (to provide neurological protection), thoracostomy (to relieve pressure in the chest causing a collapsed lung), and initiating a major trauma pathway for traumatic brain injury.

Realistic Conditions, Real Value

The setup was designed to mimic a motorway on-ramp during a severe snowstorm. Snow machines created strong winds, noise, and visibility issues, and temperatures maxed at –5 °C, with wind chill taking it lower still. Communication was difficult, movement up and down the slope was physically demanding, and accessing patients required careful coordination.

Responders were dispatched in staggered waves to reflect realistic travel times. When we were tasked, BHECCS and the critical care lead were already on scene, actively managing patients. A JESIP command structure was in place, and regular updates ensured all agencies were working from the same plan. Fire crews secured unstable vehicles using rope and pulley systems, and HART teams provided additional clinical care, supported access, and brought in equipment for safe slope working.

The presence of live volunteers as patients significantly added to the realism, and experienced critical care colleagues acted as facilitators, providing clinical updates and cues to keep the scenario evolving in real time.

The Importance of Training Together

Multi-agency training like this plays a crucial role in testing the plans and procedures we already have in place for mass casualty events. It allows teams to identify what works well, highlight areas for improvement, and adapt strategies in a controlled, but highly realistic environment. These exercises also help build trust, understanding, and communication between agencies — all of which are essential during real incidents.

Key Learning Points

Exercises like this are an essential part of maintaining readiness for large-scale incidents. Key takeaways from our perspective included:

• Scene access and egress: Moving patients up or down steep, snow-covered ground raised important questions around the safest and most efficient ways to extract casualties.
• Kit management: Staging equipment in accessible areas and thinking carefully about what to carry in can save valuable time.
• Multi-agency coordination: Effective collaboration with fire, ambulance, police, and search and rescue colleagues meant teams could focus on their roles while contributing to a shared response.
• Clinical practice in extreme environments: Performing complex procedures in cold, noisy, and unstable conditions adds a layer of challenge not always present during training – and helps refine skills and decision-making under pressure.

Final Thoughts

The exercise was incredibly well planned and delivered. It was encouraging to see how closely the scenario mirrored our experiences on real incidents – and it gave us the opportunity to test our systems, challenge our assumptions, and build even stronger relationships with colleagues from other agencies.

Everyone involved contributed to making it a truly productive day. The enthusiasm was clear, and many teams were keen to continue even beyond the scheduled end. This kind of training ensures that when major incidents do happen, we are better equipped to respond quickly, safely, and with the best possible care for our patients.

We’re extremely grateful to the organisers and everyone who took part.

By Shaun Roerig, Critical Care Paramedic

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