Dangerous goods - The philosophy on safe carriage of dangerous goods
The philosophy on safe carriage of dangerous goods
Dangerous goods can be carried safely by air transport providing certain principles are adopted. The rules are intended to provide a level of safety without placing an aircraft or its occupants at risk. They try to ensure that, should an incident occur, it does not lead to an accident.
In general dangerous goods are divided into various classes or divisions according to the hazard they present. These include:
- too dangerous ever to be carried on an aircraft;
- forbidden in normal circumstances but may be carried with the permission of the aviation regulator and subject to strict conditions being met;
- restricted to carriage only on cargo aircraft; and
- carried on either a passenger or cargo aircraft.
Dangerous goods restricted to transport by cargo aircraft are almost always in larger quantities per package than allowed on passenger aircraft. Generally no restriction is placed on the number of packages, but there are provisions for stowage, like keeping incompatible items segregated. Using cargo aircraft allows the goods to be more accessible during flight and gives the flight crew the ability to consider a greater range of emergency actions than possible on a passenger aircraft.
Rules on transporting dangerous goods
The general rules on which the air transport of dangerous goods are based are produced by the United Nations and, in the case of radioactive materials, by the International Atomic Energy Agency (IAEA). The United Nations system ensures compatibility between the international modes of transport so a consignment may be carried by more than one mode without having to reclassify or repack. Modifications are made to the system to take into account the peculiarities of air transport, while keeping in mind the need to ensure modal compatibility.
There are packing requirements of a general nature and specific packing instructions. Together these are intended to ensure the safety of dangerous goods in air transport. Packing requirements apply in almost all circumstances. The packing instructions mostly use UN specification packagings which must meet performance standards. When dangerous goods are in limited quantities these may not be required.
There is usually a wide choice of inner and outer packagings and single packagings are often permitted. Sometimes very restrictive packagings, a select few types or triple packagings are required. Generally the quantity of dangerous goods which can be placed into an inner packaging and a complete packaging is strictly controlled. When dangerous goods are consigned in limited quantities, a lower standard of pacakaging may be permitted.
After dangerous goods have been packed, the packages are marked with essential information, including the proper shipping name and the UN number, and labels depicting all the potential hazard(s) of the contents are affixed. This is to ensure packages containing dangerous goods can be recognised and warning given of the potential hazard(s) without relying on information on accompanying documents. There is a dangerous goods transport document which accompanies most consignments to provide detailed information about the goods and so that if required there is a seperate means of identifyign the contents of packages.
The pilot-in-command is informed of what dangerous goods are on board, since they need to be considered in an emergency. If one does occur, the pilot needs to notify air traffic services in order to aid the response to the emergency. In the event of an accident or incident, information is provided by the operator to the relevant authority as quickly as possible to ensure that any hazard arising from the dangerous goods is minimised.
Training is an important aid to understanding the philosophy and requirements of the regulations. There is a need for everyone concerned to receive training either for general familiarisation or to provide detailed knowledge. Dangerous goods are very unlikely to cause a problem when they are prepared, handled and carried in accordance with the regulations.
Dangerous goods accidents or incidents must be reported so that an investigation by the relevant authority can establish the cause and take action to prevent a recurrence. Any weakness in the regulations has to be identified.