The Loading Decision at the Last Minute
A cargo aircraft is being loaded for a flight. The load plan shows a pallet of UN1017 Chlorine, Class 2.3, PG none, 500 kg, and a pallet of UN1965 Hydrocarbon gas mixture, liquefied, n.o.s., Class 2.1, 400 kg, positioned adjacent to each other in the same hold. A third pallet contains UN1263 Paint, Class 3, PG II, 300 kg, positioned two positions away. The aircraft has a main deck and a lower deck; the chlorine is on the main deck, the hydrocarbon gas is on the lower deck directly beneath it, and the paint is on the main deck. The loadmaster asks whether the arrangement is acceptable, noting that 'they are all in separate pallets, so segregation is fine'.
1. Evaluate the segregation of the three dangerous goods consignments and identify any conflicts.
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The loadmaster's 'separate pallets' reasoning is wrong - segregation is about distance and compatibility, not about whether goods share a pallet.
Chlorine (Class 2.3, toxic) and hydrocarbon gas (Class 2.1, flammable): These are both Class 2 gases but with different subsidiary risks. Toxic and flammable gases must be segregated so that a leak from one does not create a compounded hazard. Placing the flammable gas directly beneath the toxic gas on the lower deck is a vertical adjacency that defeats segregation - a leak from the toxic pallet could migrate downward, and a fire from the flammable pallet could affect the toxic pallet above.
Paint (Class 3): Flammable liquids must be segregated from toxic gases. Two positions away may or may not meet the required separation depending on the aircraft's hold dimensions, but the loadmaster must verify against the segregation table rather than assume.
The arrangement as described is not acceptable without re-positioning.
2. What loading principles should the loadmaster apply, and what should happen before the flight departs?
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The loadmaster should apply the DGR segregation principles:
- Consult the segregation table for the specific class combinations (2.3 vs 2.1, 2.3 vs 3, 2.1 vs 3) and apply the required separation distances or 'away from' / 'separated from' criteria.
- Keep toxic gases away from flammable gases and flammable liquids - ideally in different holds or with the required distance.
- Load the most hazardous items where they can be monitored and where emergency access is possible.
- Verify the load plan against the NOTOC (Notification to Captain) so the pilot knows the positions of the toxic and flammable cargo.
Before departure, the loadmaster must re-position the pallets to satisfy segregation, update the load plan and NOTOC, and have the loading supervisor confirm the final arrangement. If the required separation cannot be achieved on this aircraft, one of the consignments must be offloaded.