Altor guide · 2026-09-11

Segregation: chemicals that cannot share a container

Each carton is legal. UN 1090 Acetone, Class 3, packing group II, packed to passenger packing instruction 353 at 5 L. Next to it, a fully regulated UN 3480 lithium ion battery package for cargo aircraft, packing instruction 965. The dock stretch wraps both onto one pallet. The inner specification marks are correct. The combination is not. The freight stops.

What the regulation actually requires

Segregation is three questions. Can these materials share one outer packaging. Can the closed packages share one overpack. Can they sit next to each other on the aircraft, or in the same highway vehicle. 49 CFR 173.22 still places classification on the offeror. A legal inner box does not answer the other two.

Mixed packing is the first check. 49 CFR 173.21(e) forbids putting a material in the same packaging, freight container, or overpack with another material if mixing is likely to cause a dangerous evolution of heat, flammable or poisonous gases or vapors, or corrosive materials. 49 CFR 173.24(e)(4) is the mixed contents rule. ICAO TI Part 4, Chapter 1, 1.1.8 is the air chemistry test. ICAO TI Part 4, 1.1.9 and IATA DGR 5.0.2.11 then allow different dangerous goods in one outer packaging only if they do not react, they do not require segregation under ICAO TI Table 7-1 or IATA DGR Table 9.3.A, each packaging is permitted by its packing instruction, and the Q value does not exceed 1. Q is each net quantity divided by that substance's list maximum for the aircraft type, then added. IATA DGR 8.1.6.9.2(f) wants that figure, rounded up to one decimal place, on the Shipper's Declaration. 49 CFR 172.404 still wants a label for each class.

A worked mixed packing that can pass those gates. UN 1090 Acetone, packing group II, 2 L, passenger maximum 5 L under packing instruction 353. UN 1263 Paint, packing group II, 2 L, same passenger maximum. If they do not react dangerously, Q is 0.4 plus 0.4, which is 0.8. Swap the paint for UN 1486 Potassium nitrate, Class 5.1, packing group III, passenger packing instruction 559 at 25 kg, and Table 9.3.A stops the combination before Q is run. Class 3 versus Division 5.1 is an X on the air table.

The overpack is the second check. IATA DGR 5.0.1.5 will not let packages that Table 9.3.A keeps apart share one handling unit. 49 CFR 173.25(a)(5) is stricter for packing group I Class 8 corrosives and packing group I Division 5.1 oxidizers: they may not be overpacked with any other materials.

Aircraft stowage is the third check. ICAO TI Part 7, Chapter 2, 2.2.1 and Table 7-1, IATA DGR 9.3.2 and Table 9.3.A, and 49 CFR 175.78 are the air maps. An X means the packages may not sit next to each other, in contact, or in a position that would let leaked contents interact. 49 CFR 175.78(b)(2) and IATA DGR 9.3.2.1.3 put UN 3090 and UN 3480, packed to the fully regulated methods those paragraphs name, in that X column against Class 1 other than Division 1.4S, Division 2.1, Class 3, Division 4.1, and Division 5.1. UN 3480 is passenger forbidden. On cargo aircraft it still cannot sit against that acetone carton.

Class 6, Class 7, and most of Class 9 are not in the air table. That blank is not permission to mix. UN 1689 Sodium cyanide, solid, Class 6.1, packing group I, plus UN 1830 Sulphuric acid with more than 51% acid, Class 8, packing group II, is the highway example in 49 CFR 177.848(c): cyanides may not be stored, loaded, or transported with acids if the mixture would generate hydrogen cyanide. 173.21(e) reaches the same chemistry in a packaging, freight container, or overpack, on any mode. Highway 49 CFR 177.848 uses a different map. An X means those materials may not share the same transport vehicle. A 177.848 X is not a 175.78 X. One keeps the materials off the same truck. The other keeps them from touching on the aircraft.

The mistake people make

Desks treat a legal inner box as a hall pass for the pallet. The specification marks are correct, so the wrap is assumed to inherit that. They copy a highway load plan onto an air booking. They put UN 3480 next to a Class 3 carton. They mix acid and cyanide because Class 6 is not printed on Table 9.3.A. They skip the Q value. They overpack a packing group I corrosive with a solvent carton, which 173.25(a)(5) forbids.

A mixed consignment that fails Table 9.3.A or 173.21(e) parks freight at the cargo terminal. What to do after a rejection sits at https://altor.consulting/rejected.html.

How to fix it

List every UN number, class, and packing group on the consignment before anyone stretches film. Open the table that matches the actual mode. Air is IATA DGR Table 9.3.A and 49 CFR 175.78. Highway is 49 CFR 177.848, including paragraph (c). Then run 49 CFR 173.21(e) even if the table cell is blank.

If two dangerous goods will share one outer packaging, confirm IATA DGR 5.0.2.11. Calculate Q against the passenger or cargo maxima for this booking. Write the rounded Q value per IATA DGR 8.1.6.9.2(f). Label for every class per 49 CFR 172.404. If the unit is an overpack, apply Table 9.3.A first, then 173.25(a)(5). UN 3480 packed to the methods in 175.78(b)(2) does not share film with UN 1090.

Walk the paper against the unit in the same order IATA DGR 9.1.3 will. If you cannot stand behind that combination under 49 CFR 172.204 and IATA DGR 8.1.6.12, split the consignment.

Do not offer a mixed pallet whose hazard labels the load planner cannot stow.

Altor pre-checks completed Dangerous Goods Declarations line by line against the current regulations and returns a written report, with every finding cited, within one business day. You keep the pen. altor.consulting

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