IATA Hazard Classes 1–9 — Aviation Dangerous Goods Reference

The nine UN hazard classes form the backbone of IATA Dangerous Goods Regulations. Use this index to navigate to the class-specific guide for any aviation MRO part.

What is a hazard class?

A hazard class is the UN classification that describes the primary type of risk a dangerous good presents during transport. The same nine-class system is used by IATA DGR for air, IMDG for sea, ADR for road and RID for rail. Within most classes the UN system also defines divisions and packing groups that refine the severity and dictate which packing instructions apply.

Browse by class

Regulatory review: Aligned with IATA DGR 2026 edition · Last reviewed: May 2026

Don't know the class of your part?

DG Copilot identifies the UN number, hazard class and air transport status from a part number.

This information is provided for guidance only. Always verify against the current IATA DGR edition. Final classification must be validated by a certified DG specialist.