Name Acronym Description

At the time, or as soon after the event as practicable

Control line

Control lines are constructed or natural barriers, including treated fire edges, which are used to control a fire. They can be constructed manually, mechanically or by applying water or retardants

Convection column

A rising column of pre-heated smoke, ash, particles and other debris produced by a fire

Critical National Infrastructure CNI

Critical National Infrastructure is a sub-set of critical infrastructure, and describes those elements of critical infrastructure which have been identified by Government as being of strategic national importance to essential service delivery. The loss or compromise of these assets would have a severe, widespread effect, impacting on a national scale.


A substance used to obtain temperatures far below the freezing point of water (less than -78oC).

Dead fuels

Fuels with no living tissue. The moisture content of dead fuels is mostly controlled by external weather conditions, such as relative humidity, precipitation, temperature, and solar radiation

Decontamination area

Area containing fire and rescue service (and possibly other emergency service) decontamination personnel, equipment and structures. It is a suitable area initially established outside the inner cordon, at first uncontaminated by the initial release, that becomes contaminated by the managed and controlled movement of people who require decontamination. Before decontamination commencing, the inner cordon will be adjusted to encompass the decontamination area.

Defence Accident Investigation Branch DAIB

Conducts impartial and expert no-blame safety investigations across defence organisations to ensure that causal factors are identified and understood as quickly as possible, and recommendations made to prevent recurrence and enhance safety, whilst preserving operational capability. (Formerly known as the Military Air Accident Investigation Branch (MilAAIB)

Defence Safety Authority DSA

Brings together the Defence Safety and Environment Authority (DSEA), the Military Aviation Authority (MAA) and the newly established Defence Fire Safety Regulator (DFSR) to form an independent authority that provides defence organisations with a single, independent focus for safety and environmental protection.

Definitive care

The completion of recommended medical treatment

Deliberate reconnaissance

Deliberate reconnaissance is distinct from scene assessment, which is a specific activity carried out before any formal structures being in place and as a necessary part of the initial response. Deliberate reconnaissance differs for each of the different agencies involved; for example, the police service may deploy for deliberate reconnaissance of a building or for the recovery of evidence, whereas the fire and rescue service will primarily deploy for substance analysis and identification.

Department for Environment, Food and Rural Affairs DEFRA

The Lead Government Department responsible for policy and regulations on the environment, food and rural affairs. Is also responsible for minimising the impact of emergencies on food production, fishing and farming.

Direct Electronic Incident Transfer DEIT

Information can be transferred electronically to various agencies instantaneously providing a clear understanding of assistance required.

Distribution network operators DNOs

Companies that own and operate the distribution network of towers and cables that deliver electricity from the national transmission network to homes and businesses. They do not sell electricity to consumers.


An instrument that records the total amount of gamma radiation received

Drain earth

A fixed or portable earthing device applied for purpose of protection against voltages from transmission towers or poles.

Drogue gun

A device that fires the initial parachute of an ejection seat in an aircraft


An unmanned aircraft system or an aircraft without a human pilot aboard. The flight of a drone may be controlled either by remote control from an operator or by onboard computers.

Duration table

Duration tables and/or calculators are provided as a guide to the average duration of a BA cylinder, based on the amount of air likely to be used by a BA wearer at a given incident type (ie normal fire service operations, or complex and/or strenuous BA wear involving sustained increased physical activity).


This should be requested where crews need to go within one metre of electrical traction current after the section has been isolated. This will remove the risk of any residual current remaining.

Ebb current

Once high tide occurs, the ebb current (outgoing tide) will start. This current moves away from the shore


An eddy is the swirling of a fluid and the reverse current created when the fluid flows past an obstacle. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object. Fluid behind the obstacle flows into the void creating a swirl of fluid on each edge of the obstacle, followed by a short reverse flow of fluid behind the obstacle flowing upstream, toward the back of the obstacle. This phenomenon is most visible behind large
emergent rocks in swift-flowing rivers


Force or wind generated behind a jet engine, particularly on or before take-off when high or full power is set, but also when the aircraft is taxiing

Electro-explosive device EED

Any device that is initiated electrically to provide an explosive or pyrotechnic effect; such devices may be associated with, or form part of, an explosive armament store or may be an explosive component in an aircraft or equipment system, e.g. an explosive cartridge in a fire extinguisher or a miniature detonating cord (MDC)

Electronic Communications Resilience & Response Group EC-RRG

Body hosted by the Department for Business Innovation and Skills to plan for risk within the telecommunications sector and to facilitate co-operation in maintaining the national infrastructure in an emergency