Limitations and Classification: What May Fly and How It Is Categorized
What this domain covers
This domain covers the limitations on dangerous goods (forbidden items, passenger vs. cargo aircraft, quantity limits, and hidden dangerous goods) and the classification of articles and substances into the nine hazard classes and their divisions.
Concepts to master
- The nine classes and their divisions. Explosives (1, with compatibility groups), gases (2.1 flammable, 2.2 non-flammable/non-toxic, 2.3 toxic), flammable liquids (3), flammable solids/spontaneously combustible/water-reactive (4.1, 4.2, 4.3), oxidizers and organic peroxides (5.1, 5.2), toxic and infectious substances (6.1, 6.2), radioactive material (7), corrosives (8), and miscellaneous (9, including lithium batteries and dry ice).
- Packing groups. PG I, II, III reflect degree of danger for classes 3, 4, 5.1, 6.1, 8, and some 9. PG I is greatest danger.
- Passenger vs. cargo aircraft. Many entries have different quantity limits per package; some are forbidden on passenger aircraft. Questions often hinge on which column applies.
- Forbidden goods and hidden dangerous goods. Some items are forbidden entirely; others are commonly undeclared (e.g., in baggage or general cargo). Recognizing hidden dangerous goods is a frequent acceptance trap.
- Special provisions. These modify or add conditions to an entry and must be read with the entry, not ignored.
Traps and a rule of thumb
Traps include confusing divisions within a class, misapplying packing groups to classes that don't use them (e.g., class 2, 7), and assuming a substance is permitted because it appears in the list without checking the aircraft column and quantity limits. Rule of thumb: classify first, then check limitations (aircraft type, quantity, special provisions) - never the reverse.
Worked example: A flammable liquid assigned PG II has a lower per-package limit on passenger aircraft than on cargo aircraft. Always confirm the aircraft column before quoting a limit.