Name Acronym Description
Flame length

The total length of a flame measured from its base at ground level to the flame tip. Flame length will be greater than flame height if flames are tilted due to wind or slope

Fleet Diving Squadron FDS

RN bomb disposal unit, specialising in underwater Explosives Ordnance Disposal (EOD)

Force Incident Manager FIM

Tactical role within a Police service when responding to a major or critical incident.

Fourth rail

Occasionally a fourth rail between the running rails may be found which acts as a return circuit that may carry a current of up to 250 volts DC.

Fractional horsepower motor FHP

An electric motor with a rated output power of 746 watts or less.

Free surface effect

Free surface effect is the change in stability of a vessel caused by liquids moving about freely in a tank or hold. As a vessel rolls, liquids in tanks or breached compartments accentuate the roll by moving freely from side to side of the tank accumulating first on one side and then the other, and may adversely affect the stability of the ship.

Fuel break

An existing, planned change or discontinuity in fuel that will reduce the likelihood of combustion, fire intensity and/or the rate of firespread.


Airborne solid particles (usually less than 0.0001mm) that have condensed from the vapour state.

General aviation

A term used to describe all aircraft that weigh below 5700kg without fuel loading.

G-force limiter

Reduces the force of the seat belt above a certain threshold, in conjunction with belt tensioners

Girt bar

Metal bar that connects an emergency slide to the fuselage of an aircraft

Glasgow Coma Scale GCS

The Glasgow Coma Scale is a more in-depth way than AVPU used to assess a casualty's true level of responsiveness

Global Maritime Distress and Safety System GMDSS

Internationally agreed set of safety procedures, types of equipment, and communication protocols used to increase safety and make it easier to rescue distressed ships, boats and aircraft

Globally Harmonised System GHS

Globally Harmonized System of classification and labelling of chemicals. This is a UN scheme aiming to have, worldwide, the same criteria for; classifying chemicals according to their health, environmental and physical hazards; and hazard communication requirements for labelling and safety data sheets. The GHS is not a formal treaty, but instead is a non-legally binding international agreement. Therefore countries (or trading blocks) must create local or national legislation to implement the GHS.

Government Technical Advisor GTA

A senior official, usually from HSE’s Nuclear Directorate who attends the Strategic Co-ordination Centre to provide independent and authoritative advice to the police and other authorities handling the off-site response to a nuclear emergency.

Ground fire

A fire burning below the surface of the ground

Ground fuels

Any fuel below the surface fuel layer, normally within the soil. Examples of ground fuels include organic matter, tree roots, shrub roots, rotting wood and peat

Ground power unit GPU

A mobile power unit used by aircraft parked on the stand.

Haemostatic agents

A variety of chemicals that are designed to stop the flow of blood from open vessels

Hazard identification number HIN

Used to generically describe the hazards associated to dangerous goods transported in accordance with the European transportation of dangerous goods regulations. Sometimes referred to as the Kemler code.

Hazard manager

A weather information interface provided by the Met Office. It provides a range of services that help authorities prepare for and respond to emergency incidents that are caused or influenced by the weather. It contains access to FireMet and CHEMET.

Hazardous Area Response Teams HART

Specially recruited and trained personnel who provide the ambulance response to major incidents involving hazardous materials, or which present hazardous environments, that have occurred as a result of an accident or have been caused deliberately.

Health and Safety Executive HSE

The Health and Safety Commission (HSC) and the HSE are responsible for the regulation of almost all the risks to health and safety arising from work activity in Great Britain.

Health and Safety Executive’s Nuclear Directorate HSE ND

HSE ND seeks to secure the protection of people and society from the hazards of the nuclear industry, by ensuring compliance with relevant legislation and by influencing the nuclear industry to create an excellent health, safety and security culture.It achieves this through:
• Working with other regulators and agencies
• Issuing licenses for various aspect of nuclear energy and materials
• Approving security arrangements within the industry and ensuring compliance with those arrangements
• Overseeing the UK’s international commitments on the peaceful use of nuclear energy
• Engaging with all stakeholders in an open and transparent way to inspire confidence in their work

Health Protection Agency HPA

The Agency identifies and responds to health hazards and emergencies caused by infectious disease, hazardous chemicals, poisons or radiation. It also makes sure the nation is ready for future threats to health that could happen naturally, accidentally or deliberately