Major Incident Cordon & Perimeter Planner

Incident Parameters

CAD-2026-GL7

Incident Preset Scenario Calibrated against UK Explosives Act and Home Office JESIP guidelines. Hazard Classification

Estimated TNT Equivalent (W): 120 kg

Scales blast overpressure, fragment dispersion, and cordon requirements.

Wind Bearing / Plume Vector: 245° (WSW @ 14 kt)

Directs toxic particulate drift and downwind exclusion sector.

Structure Density & Terrain: Semi-Open Airfield / Rural

Tactical Overlays:

Overpressure Rings Cordon Roadblocks Downwind Plume Sector JESIP FCP & RVP

System ready. Drag the epicenter or checkpoints on canvas.

Inner Cordon: 185 m

Outer Cordon: 550 m

Clearance Area: 0.95 km²

Inner Cordon (Hot Zone - Explosive Hazard)

Outer Cordon (Warm Zone - Multi-Agency Access)

Precautionary Evacuation Limit

Forward Command Post (FCP)

Rendezvous Point (RVP)

Police Road Closure Cordon

Inner Hot Cordon Radius 185 m Strict EOD/Armed Police only

Outer Security Perimeter 550 m Containment & media staging

Calculated Glass Hazard 810 m 0.5 psi facade break risk

Cordon Roadblocks Req. 6 Units 12 Officers on perimeter points

JESIP Joint Decision Model & M/ETHANE Protocol

LIVE BRIEFING SYNCHRONIZED

MMajor Incident Declared:

YES - Multi-agency Tier 2 response active under UK Explosives Act.

EExact Location:

Grid Reference SU 152 984, North Perimeter Road, RAF Fairford, Gloucestershire.

TType of Incident:

Suspected vehicle explosive cache, potential secondary improvised devices.

HHazards Present:

High-explosive detonation risk, blast wave, fragmentation, hazardous fumes downwind.

AAccess Routes:

Ingress via A417 southbound to primary RVP; Whelford Rd closed at perimeter.

NNumber of Casualties:

Zero confirmed active casualties; suspect detention in progress; evacuation ongoing.

EEmergency Services:

Gloucestershire Constabulary, MOD Police, EOD (11 Regt RLC), Glos Fire & Rescue, HART.

Operational Methodology & Equations

Blast overpressure and safe standoff zones rely on the standard Kingery-Bulmash scaled distance formula: Z = R / W^(1/3), where R is distance in meters and W is TNT mass equivalent in kilograms.

Inner Cordon (Hot Zone: EOD & Neutralization)

Calculated to limit primary blast overpressure to > 5.0 psi (lethal fragment threshold and severe structural failure). Only accredited Explosive Ordnance Disposal (EOD) and specialist tactical firearms officers are permitted inside once declared.

Outer Cordon (Warm/Cold Boundary: Multi-Agency Perimeter)

Established at the 1.0 psi pressure boundary to prevent flying glass injuries and severe facade collapse. This boundary demarcates the sterile operational area where ambulance triage, staging, and forward command are situated.

JESIP Interoperability Principles

The UK Joint Emergency Services Interoperability Principles mandate clear shared situational awareness between Police, Fire, Ambulance, and Military EOD units.

Forward Command Post (FCP) Standoff

The FCP must be established outside the glass hazard contour (> 0.5 psi), upwind or cross-wind of the threat origin, with unobstructed radio line-of-sight and separate access routes for heavy emergency response assets.

Public Evacuation & Road Blockages

All civilian thoroughfares intersecting the outer perimeter require dedicated cordon officers. Displaced civilian populations inside the inner sector must be routed away from downwind toxic dispersion corridors.