Hazard Air transport incidents
Knowledge and understanding
|Air transport incidents||
Understand all associated hazard knowledge
The term aircraft includes:
- Rotary-wing such as helicopters and autogyros
- Hot air balloons
- Unmanned aircraft systems (known as drones)
The list above covers both civil and military aircraft. Other agencies may use alternative terms for their own requirements, but the definitions above are deemed the most appropriate ones for fire and rescue services on which to base their risk assessments and planning assumptions.
Classification of aircraft emergencies differ between those used by the Civil Aviation Authority (CAA) and those used by the military authorities.
Fire and rescue services should be aware of the aerodromes within their area, or neighbouring areas, which might have differing aircraft incident categories; this may have an impact on mobilising and predetermined attendance.
Aerodromes in the UK fall into two categories – refer to Gain an understanding of local aerodromes.
For aerodromes covered by EASA regulations, the guidance relating to the areas adjacent to them is covered by Acceptable Means of Compliance and Guidance Material to Authority, Organisation and Operations Requirements for Aerodromes.
For aerodromes that are not EASA certified, the guidance relating to the areas adjacent to them is covered by arrangements found in the Civil Aviation Authority publication CAP168.
The Air Accident Investigation Branch (AAIB) is part of the Department for Transport and is responsible for investigating civil aircraft accidents and serious incidents within the UK. It focuses its investigation on determining the cause of an air accident or serious incident and then makes recommendations intended to prevent a reoccurrence. It does not apportion blame or liability.
The Ministry of Defence is responsible for investigating accidents involving military aircraft through the Defence Accident Investigation Branch (DAIB), although in certain circumstances the Air Accident Investigation Branch (AAIB) may also investigate accidents involving military aircraft.
Personnel may have limited experience of attending aircraft accidents, which may impact on the effectiveness of them dealing with this type of incident.
Incidents on or adjacent to aerodromes
Fire and rescue services will be called to aircraft accidents on, or adjacent to, aerodromes, due to the inherent hazards of aircraft taking off or landing. These incidents will have a rapid emergency response from Category 1 and 2 responders. The aerodrome rescue and fire fighting service (RFFS) has protocols to deal with these types of incidents; therefore fire and rescue service intervention needs to be fully interoperable with these protocols.
Aircraft accidents on or adjacent to aerodromes are likely to be more controlled in comparison with the challenges faced when dealing with an aircraft accident away from aerodromes, where the aerodrome RFFS or Ministry of Defence are not in attendance.
It is usually lower speed or lower height accidents that occur on or around the aerodrome, as the aircraft is either taking off or landing. This may mean that aircraft are more likely to be recognisable, significantly intact and accessible for rescue, with survivability relatively high. However, there will be occasions when the aircraft pilot will be forced to make an emergency landing away from a designated landing area.
High speed or higher height accidents often result in complete destruction of the aircraft, with wreckage distributed over wide areas. Fire may occur in several areas, and survivability rates are expected to be low.
Incidents off aerodromes
Air accidents off aerodrome may present additional hazards or increase the risks to fire and rescue service personnel, including:
- Difficulty of access and egress at accident sites
- Hazardous or exposed ground conditions
- Difficult environments such as water, cliffs, hillside, forest, woodlands or fields
- Damaged utility networks
- Lack of water supplies
- Wreckage trail
- Multiple casualties
- Difficult access to the aircraft and casualties
- Hazardous materials
- Environmental risks
- Difficulties in preserving evidence
Flying displays and special events
Civil, military and ex-military aircraft may be used in flying displays or at special events, such as air shows.
Information about the role of local emergency services is provided in the Civil Aviation Authority publication, CAP 403: Flying Displays and Special Events: Safety and Administrative Requirements and Guidance.
The event organiser is responsible for the production of an emergency plan, and the production and circulation of risk assessments for all contractors and emergency services working at the event location, or in the adjacent affected areas.
Aircraft engines are mainly jet engines or propeller engines, and are constructed from numerous metals, alloys and polymer composites. Whether running or isolated, they may present hazards including:
- Fuel pumps and pipelines
- Hydraulic pumps and pipelines
- Oil pumps and pipelines
- Electrical components and high energy ignition systems
- High pressure compressors
- Moving fans
- Jet engine air intake and exhaust efflux zones
- Noise – see Operations: Noise
- Projectile hazards
- High temperatures
Propellers should be cordoned off and treated as a hazard throughout the incident; they may still be operable and should not be approached. Any movement on a propeller can cause fuel to be pumped through the fuel line systems, which may generate ignition sparks, causing the engine to start or turn over.
The extent of the hazards presented by the air intakes and exhaust gases of jet engines will depend on the size the engine. The size of the hazard areas in front of and to the rear of jet engines will also vary on the size of the engine.
Most engines are encased in a cover that has opening cowlings for access to the accessory section; these cowlings have the potential to swing open if disturbed as a result of an accident.
Aircraft fuel systems
Most aircraft have a fuel system on board. The volume and type of fuel carried will depend on the aircraft, but the hazards will be similar; volumes of fuel in a large aircraft may exceed 300,000 litres.
Aviation fuels are specialised types of petroleum-based fuel used to power aircraft. They are refined to a higher specification under greater quality control than fuels used in less critical applications, such as heating or road transport. All aviation fuels contain specified small quantities of various additives such as corrosion inhibitors, static dissipaters, and anti-freezing substances.
Aviation fuel fires reach peak intensity very rapidly as the fuel develops intense heat when burning. Aircraft fuels fall broadly into two types:
- Aviation gasoline (AVGAS)
- Jet fuel
AVGAS is the most commonly used fuel for piston engines. Some gas turbines can run on AVGAS but it is not the fuel of choice and is normally only used in the case when kerosene or jet fuel is not available. AVGAS contains a highly toxic lead additive in order to achieve high octane ratings and is coloured according to the grade.
AVGAS is broadly similar to automotive gasoline but subject to much more rigorous quality control. The most common form of AVGAS has an octane rating of 100; this flashpoint is the same as that of automotive gasoline and there is a significant danger of combustion if it is not handled carefully. Although there are many more aircraft using AVGAS than use jet fuel, they are almost exclusively light aircraft.
Jet fuel is similar to kerosene, and has a much higher flash-point than gasoline, such as AVGAS, used in piston-engine aircraft. This is an important safety feature, in that the risk of fire in general use, and especially following an accident, is much lower for turbo-jet aircraft.
Jet fuel is designed for use in aircraft powered by gas-turbine engines. It is clear to straw-coloured in appearance. The most common jet fuels in use are named Jet A (U.S.) and Jet A-1 (international). They are kerosene grade fuels with a flashpoint of 38°C. Commercially available Jet B has a lower flashpoint (minus 18°C.) but it also has a much lower freezing point making it very suitable for use in extremely cold environments. Fuels such as JP5 and JP7 have higher flashpoints and were developed to provide additional safety margins in specific military applications.
There are a few types of light aircraft that are fitted with diesel engines, and it is foreseeable that hybrid engines will be introduced to aviation.
Fuel spillages may be extensive and be difficult to contain. Fuel and vapours may travel some distance, and gather downwind and downhill of the scene of the incident.
The principal hazards from aviation fuel and fuel systems in aircrafts are:
- Large volumes of fuel
- Pressurised fuel lines
- Fuel remaining within the fuselage and aircraft fuel tanks
- Varying degrees of flammability, depending on the type of fuel
- Extreme radiated heat
- Escaping fuel creating running fuel fires and pool fires
- Pools of fuel not on fire
- Jettisoned fuel tanks
- Flammable or explosive atmospheres surrounding the incident
- The fuel may be corrosive, toxic or an irritant
- Environmental impact
Electrical systems are present in larger commercial and military aircraft. The primary function of an aircraft electrical system is to generate, regulate and distribute electrical power throughout the aircraft. The aircraft electrical power system is used to operate:
- Aircraft flight instruments
- Essential systems for safe operation, such as anti-icing
- Passenger services, such as cabin lighting, entertainment systems and food preparation
- Ignition systems in light aircraft
Aircraft electrical components operate on many different voltages, both alternating current (AC) and direct current (DC).
Liquid oxygen systems
Two principal types of pressurised oxygen systems are found in commercial aircraft:
- Compressed oxygen systems
- Liquid oxygen systems
The systems will be under pressure and present a significant hazard if involved in fire.
Radar systems and aerials
Radar systems with differing wavelengths and strengths may be fitted to some aircraft. Some systems may have transmitting devices in the nose cone or side pods, and some may have externally mounted dishes or scanners.
If involved in an accident, safety systems may automatically disarm such devices. However, personnel should not initially approach aircraft that are suspected to contain radar systems, until it has been confirmed that the system has been isolated.
Aerials, particularly high frequency aerials, present a hazard due to the high temperatures the cables can reach.
EMFs may interfere with fire and rescue service communications including radios, mobile phones and telemetry systems. For further information see Industry: Electromagnetic fields (EMFs).
Radioactive materials may be used in some elements of aircraft construction and may also be present in electrical and electronic equipment installed on some aircraft. Radioactive substances may also be found in aircraft targeting systems; if damaged they can leak very small amounts of radioactive material.
The probability of coming into contact with radioactive materials at aircraft incidents is small; personnel should be adequately protected by their personal protective equipment (PPE) and respiratory protective equipment (RPE).
Hydraulic or cable systems
Pressurised systems and cables run through the cabins of aircraft, usually behind interior furnishings. Any damage sustained to the interior or exterior of the aircraft could expose personnel to hydraulics or moving objects.
Older aircraft have cables under tension; these cables usually run from the flight deck to the control surfaces, such as the rudder, elevators and flaps. If these surfaces are moved by either the flight deck crew, or possibly through external actuation, these cables will move internally.
If the interior of an aircraft is damaged, cables may present an entanglement hazard.
The auxiliary power unit (APU) is normally situated in the tail of an aircraft, therefore oil and fuel lines have to pass through the aircraft.
Where hydraulic fluid systems are installed, the system may be pressurised in excess of 200 bars. Although the fluid itself is generally fire resistant, escaping hydraulic fluid can become atomised; the resultant fine mist spray may ignite. Where hydraulic systems are under pressure there is a risk of hydraulic injection.
Access is normally made through large cargo bays situated beneath the passenger deck or at the rear of the aircraft. The area may be confined as most aircraft use unit load devices. These lightweight containers are used to maximise the space in the aircraft hold.
Hazards inside a cargo hold include:
- Cargo doors may operate
- Stacked materials that may fall
- Unidentified cargo
- On-site machinery
- Unstable surfaces
- Limited access and egress
- Aircraft fire suppression systems
- Control measureOperational learning
- Control measureProduce Site-Specific Risk Information (SSRI) and emergency response plans