Which type of material is forbidden on planes unless exempt from transport rules?

• A. Radioactive material
• B. Explosives
• C. Pyrophoric liquids
• D. Packages subject to operational control during transport

Answer: (A)

The main concept is that certain dangerous goods cannot be carried on passenger aircraft unless a specific exemption is granted. Radioactive material falls into this category because it involves ionizing radiation that can pose serious health risks to people and long-term environmental hazards. Transport rules require strict containment, shielding, monitoring, and regulatory approvals, so passenger flights typically cannot accept radioactive shipments unless an authorized exemption is granted and all stringent packaging, labeling, and handling requirements are met. When such exemptions exist, they are tightly controlled and usually limited to special cases (often on cargo-only operations or under medical/research exemptions). Explosives and pyrophoric liquids are also highly restricted, but the characteristic situation described—being forbidden on planes without an exemption—most clearly applies to radioactive materials.