Navigating Section 4.2 (Blue Pages & Table Columns A–N)

Navigating Section 4.2 (Blue Pages & Table Columns A–N)

In the global air transport of hazardous materials, Section 4.2 of the IATA Dangerous Goods Regulations (DGR)—traditionally printed on blue-bordered paper and known universally as the Blue Pages—serves as the primary operational reference. Every regulated substance or article offered for commercial air transport must be identified using the List of Dangerous Goods contained in Section 4.2. Understanding the exact architecture, column layout, and data elements of this table is essential for shippers, freight forwarders, cargo acceptance agents, and safety inspectors.

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1. Table Architecture of Section 4.2

The List of Dangerous Goods is arranged in alphabetical order by Proper Shipping Name (PSN). The table is structured into fourteen columns, labelled A through N. The column descriptions themselves are printed at DGR 4.1.6, immediately in front of the List. Each row provides comprehensive statutory specifications governing how that chemical or item must be packaged, labeled, documented, and loaded onto an aircraft.

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2. Deciphering Hazard Columns (A through F)

When identifying a substance in Section 4.2, the first step is evaluating its hazard profile in Columns A through F.

Primary vs. Subsidiary Hazards

• Column C (Class or Div. with Sub Risk) carries both the primary hazard and any subsidiary risk. Acetone shows simply 3; a corrosive with a toxic subsidiary hazard shows 8 (6.1). The most common lookup error on the exam is hunting for a separate "subsidiary risk column" — there isn't one.
• Column D (Hazard Label(s)) then tells you which labels to apply: for 8 (6.1) it lists the Corrosive label first and the Toxic subsidiary label second.

The Role of Packing Groups (Column E)

Packing Groups define the packaging performance testing standards required under DGR Section 6. A PG I substance represents the highest risk level and must be enclosed in high-integrity UN Specification Packaging certified to pass stringent drop, hydraulic pressure, and stacking tests. If Column E displays a hyphen or blank space, the entry has no packing group (common for Class 2 compressed gases, Class 6.2 infectious substances, and Class 7 radioactive materials).

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3. Operational Transport Regimes: Passenger vs. Cargo Aircraft Only

Section 4.2 divides air transport authorization into three distinct operational regimes across Columns G through L, always in packing-instruction / quantity pairs:

                     +-----------------------------------+ 
                     |     Section 4.2 Transport Regimes | 
                     +-----------------------------------+ 
                                       | 
       +-------------------------------+-------------------------------+ 
       |                               |                               | 
+--------------+               +---------------+               +---------------+ 
| Ltd Quantity |               | Passenger &   |               | Cargo Aircraft| 
| (Cols G - H) |               | Cargo Aircraft|               | Only (CAO)    | 
|  Pre: 'Y'    |               |  (Cols I - J) |               |  (Cols K - L) |   
+--------------+               +---------------+               +---------------+ 

1. Limited Quantity Regime (Columns G & H — passenger and cargo aircraft)

• Applies to small quantities of low-hazard dangerous goods packaged in combination packagings that meet inner container limits.
• Packaging Instructions always begin with the prefix 'Y' (e.g., Y441).
• Packages do not require UN specification testing marks, but must display the Limited Quantity mark (black tips top/bottom with an 'Y' inside for air transport).

2. Passenger and Cargo Aircraft Regime (Columns I & J)

• Governs standard commercial passenger flights carrying public passengers and baggage.
• Strict quantity limits apply per package (e.g., 5 L or 25 kg net mass).
• Packages must be fully UN-certified specification packagings unless an exception applies.

3. Cargo Aircraft Only (CAO) Regime (Columns K & L)

• Applies to dedicated freighter aircraft carrying no passengers.
• Allows significantly larger net quantities per package (e.g., 60 L or 220 kg) or permits hazardous materials forbidden on passenger flights.
• Consignments accepted under CAO columns must bear the orange Cargo Aircraft Only handling label.

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4. Understanding 'Forbidden' Entries

If the term 'Forbidden' appears in Section 4.2 across specific columns, strict legal prohibitions apply:

• Forbidden on Passenger Aircraft: The substance displays 'Forbidden' in Columns I and J, but lists a packing instruction in Column K and a net quantity in Column L. The shipment can ONLY travel on cargo freighters, with a CAO label. If A1 appears in Column M, there is a route to passenger carriage with the prior approval of the State of Origin and the State of the Operator.
• Forbidden on Both Passenger and Cargo Aircraft: The word 'Forbidden' appears across Columns I/J and K/L. The substance is forbidden under all standard circumstances (e.g., unstable explosives, self-reactive chemicals prone to violent thermal decomposition). If A2 appears in Column M, the entry may still move on a cargo aircraft only with the prior approval of the State of Origin and the State of the Operator.

State Exemptions (Section 1.2)

Where no special provision offers an approval route, transporting a chemical marked 'Forbidden' on both passenger and cargo aircraft requires a formal State Exemption under DGR 1.2.6. Exemptions require written authorizations from the National Civil Aviation Authorities (NCAAs) of the state of origin, state of transit, state of destination, and the operator's flag state.