There are some dangerous goods than cannot be carried by air freight under any circumstances, others are forbidden under normal circumstances but may be carried with specific approvals from the States concerned, some are restricted to be carried only on all-cargo aircraft (CAO) and some can be carried on both passenger and all-cargo aircraft, subject to meeting the required conditions stated in ICAO Technical Instructions for the Safe Transport of Dangerous Goods by Air (ICAO Doc 9284).
Dangerous goods are articles or substances which are capable of posing a risk to health, safety, property or the environment and which are shown in the list of dangerous goods in ICAO Technical Instructions for the Safe Transport of Dangerous Goods by Air (ICAO Doc 9284), or which are classified according to these Instructions.
Cargo containing dangerous goods is subject to national and international regulation. Such cargo has to be properly declared and clearly identified as containing dangerous goods. Cargo declared under a general description may contain hazardous items that are not apparent.
These can be common items as:
Dangerous goods are divided into nine classes according to the hazard they present, some classes have as well divisions. A detailed list of dangerous goods is shown in ICAO Technical Instructions for the Safe Transport of Dangerous Goods by Air (ICAO Doc 9284) and it indicates the class or division into which each article falls, its acceptability for air transport and under what conditions.
In order to ensure that packages containing dangerous goods can be recognized and warning given of the potential hazard(s) without relying on information in accompanying documentation, packages of dangerous goods are marked with essential information, including proper shipping name and UN number and hazard labels showing all the potential hazard(s) of the contents.