一个真实场景:货代仓库晚上 8 点拼出一票拼柜空运货,准备凌晨入场。同一个 LD3 集装箱里塞了:一批 Class 3 易燃液体(油漆稀释剂)、一批 Class 5.1 氧化剂(漂白粉)、一批 Class 9 锂电池(移动电源)。所有外箱都贴对了标签、DGD 全部齐备、PI 也合规。 装机当天,地服一看 ULD 配载单——直接拒收。 原因:Class 3 易燃液体和 Class 5.1 氧化剂不能合装在同一 ULD 内。这是 IATA DGR 第 9 章 Table 9.3.A 的硬性规定。即便每一件单独都合规,装在一起也违规。 这种"单件都对,合装就错"的情况,每天都在全球各大货站发生。原因都指向同一个工具——Table 9.3.A 兼容性矩阵。这一篇我们把这张表怎么读、怎么用、怎么避坑,一次性拆给你看。
一、为什么需要兼容性矩阵
危险品的危险性不只取决于"它是什么",还取决于"它和谁放一起"。
举几个典型的"互相反应"场景:
- Class 3(易燃液体)+ Class 5.1(氧化剂):液体一旦泄漏接触氧化剂,可能自燃甚至小爆炸
- Class 4.3(遇水放出易燃气体)+ Class 8(腐蚀液体):腐蚀液体泄漏后,反应放出氢气,整个货舱变成爆炸气体
- Class 1(爆炸品)+ 几乎所有 Class:爆炸品本身就是高风险,几乎不能和别的 DG 同舱
- Class 7(放射性)+ 其他:放射性需要单独分隔,避免对其他货物产生辐射污染
兼容性矩阵的本质:用一张二维表,告诉你「Class X 和 Class Y 能不能装在同一空间」。
二、Table 9.3.A 长什么样
Table 9.3.A 在 IATA DGR 第 9 章「Handling」部分。它是一张 横纵都是 Class 编号 的二维矩阵。每个交叉格里有一个代码:
| 代码 | 含义 |
| 留空 / "—" | 没有兼容性限制 |
| "X" | 禁止同 ULD 装载 |
| "Y" | 允许同 ULD 但需分隔 |
| 数字 | 具体分隔距离要求 |
| 备注代号 | 特殊规则(查 9.3.A 附录) |
矩阵的横轴和纵轴都是 Class 编号(含子类:1.1-1.6 / 2.1/2.2/2.3 / 3 / 4.1/4.2/4.3 / 5.1/5.2 / 6.1/6.2 / 7 / 8 / 9)。
读法:找到你的两个货物所属的 Class,看它们交叉位置的代码。
举例:
- Class 3(易燃液体)+ Class 5.1(氧化剂)→ 通常标记为 "X" 或要求严格分隔
- Class 4.1(易燃固体)+ Class 9(杂项)→ 通常无特殊限制
- Class 2.1(易燃气体)+ Class 8(腐蚀)→ 通常允许但需分隔
具体代码以现行版 IATA DGR Table 9.3.A 为准——这张表每隔几年会有局部更新。
三、三个层级的"分隔":ULD、货舱、飞机
兼容性矩阵的"分隔"在实操中分三个层级:
| 层级 | 含义 | 谁负责 |
| 包件层 | 单件 DG 货之间的物理距离 | 货代 / 仓库 |
| ULD 层 | 同一集装箱 / 板内的货物是否兼容 | 货代 / 地服 |
| 货舱层 | 整个飞机货舱内的货物布局 | 航司 / 配载员 |
Table 9.3.A 主要约束的是 ULD 层 和部分 包件层。货舱层有更宏观的规则(如 Class 1 爆炸品的位置专门安排),由航司配载员管。
一线货代关注的核心是 ULD 层——你订一个 LD3、LD7 或 PMC 板,板内不能装兼容性冲突的货。
四、ULD 装载的 4 条铁律
ULD 装载时建议遵守的 4 条硬性原则:
1. 主类 + 次类都要查矩阵
如果一票货有次类(如 UN1796 主类 Class 8 + 次类 Class 5.1),兼容性要按主类和次类分别查一遍。任何一个组合冲突,都不能合装。
2. 同 Class 通常无内部冲突
同 Class 之间一般不冲突(除少数子类有例外)。例如 Class 3 各种易燃液体之间通常可以合装。
3. Class 1 / Class 7 几乎独立
- Class 1 爆炸品在飞机上有专门的限制位置,通常不与其他 DG 合装
- Class 7 放射性物质有严格的分隔距离要求,按辐射等级(I-White / II-Yellow / III-Yellow)有不同距离
4. 锂电池的特殊处理
锂电池虽然是 Class 9,但因为火灾风险特殊,许多航司在 OV 里额外要求:
- 大批量锂电池不与其他易燃货合装
- 锂电池 ULD 单独标识
- 与可燃货物保持物理距离
五、合装决策树:3 步搞清楚能不能合装
接到一个拼柜单,按下面 3 步走,10 分钟内能算清楚能不能合装:
`` Step 1:列出所有 UN 号 + 主类 + 次类 ↓ Step 2:两两组合,查 Table 9.3.A 矩阵 ├─ 全部留空 → 可合装 ├─ 出现 "X" → 不能合装,必须分 ULD └─ 出现 "Y" 或数字 → 可合装但需分隔 ↓ Step 3:核对承运航司 OV ├─ OV 有更严限制 → 按 OV 走 └─ OV 无额外限制 → 按矩阵执行 ``
如果你不确定具体两个 Class 的矩阵代码,可以在 OneCargoKit 的 Dangerous Goods Check 里查"Table 9.3.A 兼容性"模块——工具内置了完整的兼容性矩阵图,输入任意两个 Class 编号秒出结果,省去翻手册。一线建议是把这张表打印成 A3 海报贴在仓库墙上,每次拼柜前抬头看一眼,比每次都翻手册快得多,也比靠记忆稳得多。资深货代仓库的派工台旁边几乎都有这样一张表。除了纸质海报,也建议在公司微信群或飞书群里置顶一张电子版,方便夜班和远程同事随时查询。
六、化学反应背后的物理逻辑
很多人查兼容性矩阵只记代码,不理解"为什么不能合装"。这让你在遇到边缘情况时无法判断。下面几个最高频的冲突,背后的化学逻辑要懂:
易燃液体 + 氧化剂
氧化剂会向周围环境释放氧气或具有氧化性的成分。易燃液体本身燃烧的限制条件是"空气中的氧气浓度"——氧化剂存在时,易燃液体的着火点和燃烧速率都会显著降低和加快。如果泄漏混合,一个微小的火星就可能造成猛烈燃烧。
遇水放气物质 + 含水溶液
Class 4.3 是"遇水放出易燃气体",最典型的就是金属钠、电石。Class 8 腐蚀品里很多是水溶液(如盐酸、硫酸)。两者放一起,一旦腐蚀液体泄漏接触到 Class 4.3 包装,水会和 Class 4.3 反应放出氢气。飞机货舱内一旦氢气浓度达到爆炸极限,整架飞机面临严重威胁。
有机过氧化物 + 任何还原性 / 腐蚀性物质
Class 5.2 有机过氧化物自身就不稳定,温度升高或受到化学刺激就可能分解放热。如果有还原剂或腐蚀剂泄漏接触,分解反应可能链式扩散。这就是为什么 Class 5.2 在 IATA DGR 里有专门的温控要求和包装规则。
毒性气体 + 食品 / 医药
Class 2.3 毒性气体即使包装合规,仍存在微量泄漏风险。和食品、医药、动物饲料同舱,一旦泄漏会造成不可挽回的污染。这种组合的限制属于"概率极低但后果极重",民航零容忍。
理解了化学逻辑,你查矩阵时不只是机械对码,而是能预判风险,主动设计更安全的装载方案。这种"知其然知其所以然"的能力,是一线 DG 操作员价值的核心。
七、常见冲突组合速查表
下面这张表是一线高频遇到的「不可合装」组合,强记下来能避免 80% 拼柜错误:
| 组合 | 冲突原因 | 处理建议 |
| Class 1(除 1.4S)+ 几乎所有 DG | 爆炸风险 | 单独 ULD |
| Class 3 易燃液体 + Class 5.1 氧化剂 | 泄漏→自燃 | 分 ULD 或严格分隔 |
| Class 4.3(遇水放气)+ Class 8 液体腐蚀 | 反应放氢气 | 分 ULD |
| Class 4.2 自燃 + Class 5.1 氧化剂 | 加速自燃 | 分 ULD |
| Class 2.3 毒性气体 + 食品 / 医药 | 污染风险 | 严格隔离 |
| Class 5.2 有机过氧化物 + Class 8 腐蚀 | 引发反应 | 分 ULD |
| Class 7 放射性 + Class 6.2 感染性 | 双重危险源 | 严格分隔距离 |
| 大量 Class 9 锂电池 + Class 3 易燃液体 | 火灾叠加风险 | 部分航司禁同 ULD |
八、Section II 锂电池的"边缘情况"
跨境电商发的 Section II 锂电池在文件层面是简化处理,但它仍然是 Class 9,仍然要走兼容性矩阵。容易踩坑的几个边缘情况:
- 手机(PI 967 Section II)+ 化妆品喷雾(Class 2.1)合包 —— Class 9 和 Class 2.1 的矩阵需要查;不少航司 OV 要求物理分隔
- 移动电源大量集中装载 —— 即使是 Section II,单 ULD 内锂电池数量过多,部分航司要求拆 ULD
- 锂电池 + 干冰冷链 —— 都属于 Class 9,但低温环境会影响锂电池性能,部分航司 OV 限制合装
电商货代经常忽略这些边缘情况,等到拼柜后地服一查发现违规,整票拆柜重做。建议跨境电商在询价单上就明确标注每个 SKU 的 UN 号和电池规格,让货代在报价前完成兼容性预审。这样既减少返工,也让你跟客户的交期承诺更有底气。
九、共载(Co-loading)vs 合装(Mixing)
这两个词在一线被混用,但严格意义不同:
- 合装(Mixing in one package):多个 UN 号的 DG 装在同一外箱内
- 共载(Co-loading in one ULD):多个不同 UN 号的 DG 装在同一 ULD 内但分外箱
- 同舱(Same hold):多个 DG 在同一货舱内
合装 的规则比 共载 严得多:
- 合装需要遵守 PI 内部的「mixed packing」规则(部分 PI 不允许)
- 合装的外箱要符合所有 UN 号中最严的包装等级
- 合装时各 UN 号之间不能化学反应
共载 的规则相对宽松,主要看兼容性矩阵。
新人经常把这两个混淆。拼柜时主要看的是共载规则(Table 9.3.A),而多瓶不同 DG 装同一外箱是合装(要查 PI 自身规则)。还有一个常被忽略的层级——Overpack 合装:当你把多个已合规外箱缠膜或装入更大的纸箱合成一个"包件"时,外层 Overpack 内部仍然适用兼容性约束。新人经常以为"外面缠一层膜就能糊弄过去",地服开箱一查就露馅。Overpack 不能改变内部货物的兼容性属性,只是搬运的便利单元。
实操上的判断顺序是:先合装 → 再 Overpack → 最后共载。这三层依次过完,整个拼柜方案才算合规。任何一层短路都会在后面环节冒出来,但越往后修复成本越高。
十、ULD 标识与配载单:实操对账
每个 ULD 在装机时都会贴一张配载单(Loading Manifest),上面列出 ULD 内所有货物的:
地服核对时主要看:
- ULD 内 UN 号组合是否过 Table 9.3.A
- 单 ULD 总净重是否超 ULD 承载
- 锂电池数量是否超 OV 限制
- CAO 货是否装在 CAO ULD 内
资深货代会在派工前自己出一份模拟配载单,把 ULD 内所有 UN 号逐一过兼容性矩阵,把潜在冲突在送货前消除。
派工前如果要算每个 ULD 的最优配载(容积重 + 计费重 + 兼容性),可以用 ULD Calculator 配合 Aircraft Loading 工具做模拟。
十一、常见误区
- 误区 1:兼容性矩阵只在装机时才看 —— 错。从客户询价开始就要在心里过一遍兼容性,避免承诺合装结果到时候做不到。
- 误区 2:同一航司同一航线,规则永远一样 —— 错。航司 OV 可能因航班机型、季节、起降机场不同。
- 误区 3:Class 9 都是"轻 DG",互相之间无冲突 —— 错。锂电池 + 干冰 + 磁性材料三个都是 Class 9,但合装规则各不同。
- 误区 4:单件合规就能合装 —— 错。这是这一篇要破除的最核心误区。
- 误区 5:拼柜时合装节省成本 —— 不一定。强行合装违规的代价远高于多订一个 ULD。
- 误区 6:兼容性查一遍就够 —— 错。每次拼柜单变更(加货、减货、换货)都要重新过一遍矩阵。
- 误区 7:地服会兜底,自己不用查 —— 错。地服只做最后复核,他们打回的代价是整票货返工。
- 误区 8:Y 标记限量货可以无视兼容性 —— 错。限量货虽然简化文件,但仍然受兼容性约束(具体看现行 DGR)。
十二、实操检查清单(拼柜前 60 秒)
- [ ] 列出所有 UN 号 + 主类 + 次类
- [ ] 两两组合查 Table 9.3.A 矩阵
- [ ] 标识所有 "X" 不可合装组合
- [ ] 标识所有 "Y" 需分隔组合,估算分隔可行性
- [ ] Class 1 单独 ULD
- [ ] Class 7 按辐射等级分隔
- [ ] 锂电池数量在单 ULD 限制内
- [ ] CAO 货只放 CAO ULD
- [ ] ULD 内总净重未超承载
- [ ] 与承运航司 OV 二次核对
- [ ] 出模拟配载单 + 双人复核
十三、给三类岗位的判定方法
| 岗位 | 矩阵决策核心动作 | 输出 |
| 货代 / 操作 | 派工前过矩阵 + 出模拟配载 + 与航司核对 | 合规拼柜方案 |
| 跨境电商运营 | 多 SKU 发货时和货代提前明确组合 | 物流方案选择 |
| 航司配载员 | 装机前最终核对 ULD + 货舱布局 | 装机许可 |
给电商运营的一句忠告:很多卖家以为"合规交给货代就行"。短期没错,长期不对。一旦合作的货代换了人手或者公司,新货代不熟悉你的品类,问题就会暴露。最稳的做法是自己也建立基本的兼容性认知,至少知道自己发的几个 SKU 的 UN 号和 Class,能在询价阶段判断货代回的方案是否靠谱。
十四、合规与边界提醒
- 本文是基于公开的 IATA DGR 第 9 章 Table 9.3.A 体系做的实操梳理,不构成法律、合规或安全建议
- Table 9.3.A 具体代码以现行版 IATA DGR为准
- 各承运航司 OV 可能比矩阵更严,起运前查最新版
- 部分国家民航当局有补充规定(如对放射性、爆炸品的额外距离要求)
- 复杂多 UN 号拼柜建议由具备 DG 资质的高级操作员或航司配载员主审
十五、与海运 IMDG 段落的对照阅读
很多货代客户是多式联运——空运一段、海运一段,或者公路+空运。这种场景下,兼容性矩阵在不同模式下不完全一致:
| 模式 | 兼容性矩阵在哪 | 关键差异 |
| 空运 | IATA DGR 第 9 章 Table 9.3.A | 按 Class 二维矩阵 |
| 海运 | IMDG Code Segregation Table | 按 4 个分隔等级(Away from / Separated from / Separated by complete compartment from / Separated longitudinally by intervening complete compartment or hold from) |
| 公路 ADR | ADR 第 7 章 | 按 13 个 Compatibility Group 处理 |
实操要点:
- 一票货走海空联运,空运段按 IATA Table 9.3.A,海运段按 IMDG Segregation Table,两套都要过
- IMDG 的分隔等级比 IATA 更细,部分组合在海运允许、在空运禁止
- 跨境电商的"散货拼柜+空运段拼舱"组合是合规复杂度最高的场景
理解这些差异能帮你给客户提供更精准的多式联运合规建议,也避免被海运同事的判断误导。
十六、结尾:兼容性矩阵是 DG 链路里"看不见的指挥棒"
兼容性矩阵不像 PI 包装、DGD 那样直接出现在外箱和文件上,但它在整个 DG 链路里是最重要的隐形约束。每一次拼柜决策、每一次 ULD 装载、每一次航班配载,背后都有这张表在静静地审视。
新人最容易掉链子的不是"忘了查这张表",而是"忘了它存在"。当客户说"能不能给我装一柜拼货",资深货代第一反应是"先列 UN 号过矩阵",新人的反应是"先算装箱体积"。这两种思维差距,决定了 90% 的拼柜事故。
养成这个习惯:每次接到 DG 拼柜询价,先列 UN,过矩阵,再谈价格。这是 DG 货代的"职业本能"。把它从"知识"变成"反射",需要的不是看更多文档,而是在真实业务里反复跑。建议新人入职头 3 个月,每接一票 DG 拼柜单都自己手动出一份模拟配载,让资深同事复核,3 个月后你的速度和准确度都会上一个台阶。
下一篇我们继续:SHC 特殊操作代码(RLI / RLM / RFL / ICE 等)速查与含义——这套代码是航司、地服、货代之间的"暗号系统",懂了它你和地服的沟通效率会提升一个量级。我们下次见。
A real-life scenario: At 8 p.m., a freight forwarder’s warehouse consolidates a shipment of LCL air cargo, preparing to send it to the airport at midnight.The same LD3 container was packed with: a consignment of Class 3 flammable liquids (paint thinner), a consignment of Class 5.1 oxidizers (bleaching powder), and a consignment of Class 9 lithium batteries (power banks).All outer packaging was properly labeled, all DGDs were complete, and the PI was compliant. On the day of loading, the ground handling staff looked at the ULD loading list—and immediately refused acceptance. Reason: Class 3 flammable liquids and Class 5.1 oxidizers cannot be loaded together in the same ULD. This is a strict requirement under Table 9.3.A of Chapter 9 of the IATA DGR. Even if each individual item complies with regulations, loading them together is a violation. This scenario—where “each item is correct individually, but combined they’re wrong”—happens every day at major cargo terminals around the world. The root cause always points to the same tool: the Table 9.3.A compatibility matrix. In this article, we’ll break down exactly how to read and use this table—and how to avoid pitfalls—all in one go.
I. Why Do We Need a Compatibility Matrix?
The danger posed by dangerous goods depends not only on “what they are,” but also on “what they’re stored with.”
Here are a few typical “reactive” scenarios:
- Class 3 (Flammable Liquids) + Class 5.1 (Oxidizers): If a liquid leak comes into contact with an oxidizer, it may spontaneously combust or even cause a small explosion
- Class 4.3 (Flammable Gases) + Class 8 (Corrosive Liquids): If a corrosive liquid leaks, the reaction releases hydrogen gas, turning the entire cargo hold into an explosive atmosphere
- Class 1 (Explosives) + Virtually All Classes: Explosives are inherently high-risk and should almost never be loaded in the same compartment as other dangerous goods
- Class 7 (Radioactive Materials) + Others: Radioactive materials must be isolated to prevent radiation contamination of other cargo
The essence of the compatibility matrix: A two-dimensional table that tells you whether “Class X and Class Y can be loaded in the same space.”
II. What Table 9.3.A Looks Like
Table 9.3.A is found in Chapter 9, “Handling,” of the IATA DGR. It is a two-dimensional matrix with Class numbers along both rows and columns. Each cell contains a code:
| Code | Meaning |
| Blank / "—" | No compatibility restrictions |
| "X" | Cannot be loaded with ULD |
| "Y" | Allowed with ULD but must be separated |
| Number | Specific separation distance requirements |
| Remarks Code | Special Rules (See Appendix 9.3.A) |
Both the horizontal and vertical axes of the matrix consist of Class numbers (including subclasses: 1.1–1.6 / 2.1/2.2/2.3 / 3 / 4.1/4.2/4.3 / 5.1/5.2 / 6.1/6.2 / 7 / 8 / 9).
Instructions: Find the Class to which your two cargo items belong, and look up the code at their intersection.
Example:
- Class 3 (Flammable Liquids) + Class 5.1 (Oxidizing Agents) → Typically marked with an “X” or requires strict separation
- Class 4.1 (Flammable Solids) + Class 9 (Miscellaneous) → Usually no special restrictions
- Class 2.1 (Flammable Gases) + Class 8 (Corrosives) → Generally permitted but must be separated
Specific codes are subject to the current version of IATA DGR Table 9.3.A—this table undergoes partial updates every few years.
III. Three Levels of “Segregation”: ULD, Cargo Hold, Aircraft
In practice, the “segregation” in the compatibility matrix is divided into three levels:
| Level | Meaning | Who Is Responsible |
| Package Level | Physical distance between individual DG shipments | Freight forwarder / Warehouse |
| ULD Level | Compatibility of cargo within the same container or pallet | Freight Forwarder / Ground Handling |
| Cargo hold level | Cargo layout within the entire aircraft cargo hold | Airline / Load Planner |
Table 9.3.A primarily addresses constraints at the ULD level and, to some extent, the package level. Cargo hold levels are governed by more overarching rules (such as the designated placement of Class 1 explosives), which are managed by the airline’s load planners.
The primary focus for frontline freight forwarders is the ULD level—when you book an LD3, LD7, or PMC pallet, the pallet must not contain cargo with compatibility conflicts.
IV. The 4 Ironclad Rules for ULD Loading
Four mandatory principles recommended for ULD loading:
1. Check the compatibility matrix for both the primary and secondary classes
If a shipment contains a subclass (e.g., UN1796—Main Class 8 + Subclass 5.1), compatibility must be checked separately for both the main class and the subclass. If any combination results in a conflict, the items cannot be loaded together.
2. There are generally no internal conflicts within the same Class
There are generally no conflicts between items within the same Class (with exceptions for a few subclasses). For example, various flammable liquids within Class 3 can usually be loaded together.
3. Class 1 and Class 7 are virtually independent
- Class 1 explosives have designated restricted locations on aircraft and are generally not transported together with other dangerous goods (DG).
- Class 7 radioactive materials have strict separation distance requirements, with different distances based on radiation class (I-White / II-Yellow / III-Yellow).
4. Special Handling of Lithium Batteries
Although lithium batteries are classified as Class 9, due to their specific fire risk, many airlines include additional requirements in their Operational Instructions (OV):
- Large quantities of lithium batteries must not be stowed with other flammable cargo
- Lithium battery ULDs must be separately marked
- Maintain a physical distance from combustible cargo
V. Consolidation Decision Tree: 3 Steps to Determine Whether Consolidation Is Permitted
When you receive a consolidated shipment order, follow these 3 steps to determine within 10 minutes whether co-loading is permitted:
`` Step 1:列出所有 UN 号 + 主类 + 次类 ↓ Step 2:两两组合,查 Table 9.3.A 矩阵 ├─ 全部留空 → 可合装 ├─ 出现 "X" → 不能合装,必须分 ULD └─ 出现 "Y" 或数字 → 可合装但需分隔 ↓ Step 3:核对承运航司 OV ├─ OV 有更严限制 → 按 OV 走 └─ OV 无额外限制 → 按矩阵执行 ``
If you’re unsure of the specific matrix codes for two classes, you can look them up in the “Table 9.3.A Compatibility” module within OneCargoKit’s Dangerous Goods Check—the tool includes a complete compatibility matrix chart. Enter any two class numbers to get results instantly, saving you the trouble of flipping through the manual.Our field recommendation is to print this table as an A3 poster and hang it on the warehouse wall. Glancing at it before each consolidation is much faster than flipping through the manual every time—and far more reliable than relying on memory.You’ll find a chart like this next to the dispatch desk in almost every experienced freight forwarder’s warehouse. In addition to the paper poster, we also recommend pinning a digital version to the top of your company’s WeChat or Feishu group chats so that night shift and remote colleagues can access it at any time.
VI. The Physical Logic Behind Chemical Reactions
Many people who consult compatibility matrices only memorize the codes without understanding “why these items cannot be shipped together.” This makes it impossible to make judgments when encountering borderline cases. You need to understand the underlying chemical logic behind the following most common conflicts:
Flammable Liquids + Oxidizers
Oxidizers release oxygen or oxidizing components into the surrounding environment. The limiting factor for the combustion of flammable liquids is the “concentration of oxygen in the air”—when oxidizers are present, both the flash point and the combustion rate of flammable liquids decrease and increase significantly, respectively. If they leak and mix, even a tiny spark could cause a violent fire.
Substances that Evolve Gas on Contact with Water + Aqueous Solutions
Class 4.3 substances “release flammable gases when in contact with water”; the most typical examples are sodium metal and calcium carbide. Many substances in Class 8 (corrosives) are aqueous solutions (such as hydrochloric acid and sulfuric acid).When these two are stored together, if a corrosive liquid leaks and comes into contact with Class 4.3 packaging, the water will react with the Class 4.3 substance to release hydrogen gas. Once the hydrogen concentration in the aircraft cargo hold reaches the explosive limit, the entire aircraft faces a serious threat.
Organic Peroxides + Any Reducing / Corrosive Substances
Class 5.2 organic peroxides are inherently unstable; they may decompose and release heat when exposed to elevated temperatures or chemical stimuli. If a leak of a reducing agent or corrosive substance comes into contact with them, the decomposition reaction may trigger a chain reaction. This is why Class 5.2 has specific temperature control requirements and packaging regulations in the IATA DGR.
Toxic Gases + Food / Pharmaceuticals
Even when properly packaged, Class 2.3 toxic gases still pose a risk of trace leakage. When transported in the same cargo hold as food, pharmaceuticals, or animal feed, a leak could cause irreversible contamination. Restrictions on this combination fall under the category of “extremely low probability but extremely severe consequences,” for which civil aviation has a zero-tolerance policy.
Once you understand the chemical logic, consulting the matrix becomes more than just a mechanical process of matching codes; you can anticipate risks and proactively design safer loading plans. This ability to “not only know what to do but also why” is at the core of a front-line DG operator’s value.
VII. Quick Reference Table for Common Incompatible Combinations
The table below lists “incompatible” combinations frequently encountered on the front lines; memorizing them can prevent 80% of container consolidation errors:
| Combination | Reason for Conflict | Handling Recommendations |
| Class 1 (excluding 1.4S) + Almost all DG | Explosion risk | Separate ULD |
| Class 3 Flammable Liquids + Class 5.1 Oxidizers | Leak → Spontaneous combustion | Separate ULDs or strictly segregated |
| Class 4.3 (gas evolution upon contact with water) + Class 8 Corrosive Liquids | Reaction releases hydrogen gas | Separate into ULDs |
| Class 4.2 (spontaneously combustible) + Class 5.1 (oxidizers) | Accelerated spontaneous combustion | Separate ULD |
| Class 2.3 Toxic gases + Food / Pharmaceuticals | Risk of contamination | Strictly segregate |
| Class 5.2 Organic Peroxides + Class 8 Corrosives | Reaction hazard | Separate ULDs |
| Class 7 Radioactive + Class 6.2 Infectious | Dual-Hazard Sources | Strict separation distance |
| Large quantities of Class 9 lithium batteries + Class 3 flammable liquids | Combined fire risk | Prohibited in the same ULD by some airlines |
VIII. “Edge Cases” for Section II Lithium Batteries
Section II lithium batteries shipped via cross-border e-commerce are subject to simplified documentation procedures, but they remain Class 9 and must still undergo compatibility matrix checks. Here are several “edge cases” where mistakes are common:
- Combined shipment of cell phones (PI 967 Section II) + cosmetic sprays (Class 2.1) — Check the compatibility matrix for Class 9 and Class 2.1; many airlines’ Operational Instructions (OV) require physical separation
- Concentrated loading of large quantities of power banks — Even for Section II, if there are too many lithium batteries in a single ULD, some airlines require the ULD to be unloaded
- Lithium batteries + dry ice cold chain — Both fall under Class 9, but low-temperature environments can affect lithium battery performance; some airlines’ Operational Vouchers (OVs) restrict their combined shipment
E-commerce freight forwarders often overlook these edge cases; once the shipment is consolidated and ground handling personnel discover a violation during inspection, the entire shipment must be deconsolidated and reprocessed.We recommend that cross-border e-commerce businesses clearly indicate the UN number and battery specifications for each SKU on their RFQs, allowing freight forwarders to complete a preliminary compatibility review before providing a quote. This not only reduces rework but also gives you greater confidence in meeting delivery commitments to your customers.
IX. Co-loading vs. Mixing
These two terms are often used interchangeably in the field, but they have distinct meanings:
- Mixing (in one package): Multiple DG items with different UN numbers packed within the same outer carton
- Co-loading in one ULD: Multiple DG items with different UN numbers are loaded into the same ULD but packed in separate outer boxes
- Same hold: Multiple DG shipments are in the same cargo hold
The rules for “Mixing” are much stricter than those for “Co-loading”:
- Mixing in one package must comply with the “mixed packing” rules specified in the Packing Instructions (PI) (some PIs do not permit this)
- The outer packaging for mixed packing must meet the most stringent packaging class among all UN numbers
- There must be no chemical reactions between the different UN numbers when mixed packing
The rules for “consolidation” are relatively lenient and primarily depend on the compatibility matrix.
Newcomers often confuse these two concepts. When consolidating containers, the focus is primarily on the mixed-loading rules (Table 9.3.A), whereas packing multiple bottles of different DGs into the same outer packaging constitutes mixed packing (which requires checking the PI’s own rules).There is another often-overlooked level—overpack combined packing: when you wrap multiple compliant outer cartons in stretch film or place them inside a larger cardboard box to form a single “package,” the compatibility constraints still apply to the contents inside the outer overpack.Newcomers often assume that “wrapping the outside with a layer of stretch film will get them by,” but ground handling staff will uncover the issue as soon as they open the box. An overpack does not alter the compatibility attributes of the contents inside; it is merely a unit designed for handling convenience.
The practical sequence for assessment is: first, consolidation → then, overpacking → finally, co-loading. Only after all three layers have been verified in sequence is the entire container consolidation plan considered compliant. A failure at any one layer will surface in subsequent stages, but the cost of rectification increases the further along the process you go.
X. ULD Markings and Loading Manifests: Operational Reconciliation
Each ULD is affixed with a Loading Manifest during loading, which lists the following details for all cargo inside the ULD:
- AWB number
- UN Number
- PSN
- Number of pieces
- Net weight
- Class
- PI
During ground handling verification, the following should be checked:
- Whether the UN number combinations within the ULD exceed the limits in Table 9.3.A
- Whether the total net weight of a single ULD exceeds the ULD’s load capacity
- Whether the number of lithium batteries exceeds OV limits
- Whether CAO cargo is loaded into a CAO ULD
Experienced freight forwarders will prepare their own simulated loading plan before assigning the job, checking the compatibility of every UN number within each ULD against the compatibility matrix to eliminate potential conflicts before delivery.
If you need to calculate the optimal load for each ULD (volumetric weight + chargeable weight + compatibility) before assigning the job, you can use the ULD Calculator in conjunction with the Aircraft Loading tool to run a simulation.
XI. Common Misconceptions
- Misconception 1: The compatibility matrix is only checked during loading — Wrong. You should mentally review compatibility starting from the customer’s initial inquiry to avoid promising combined shipments that cannot be delivered later.
- Misconception 2: Rules are always the same for the same airline and route — Wrong. An airline’s Operational Guidelines (OV) may vary depending on the aircraft type, season, and departure/arrival airports.
- Misconception 3: All Class 9 items are “light DG” and do not conflict with each other — Wrong. Lithium batteries, dry ice, and magnetic materials are all Class 9, but their combined loading rules differ.
- Misconception 4: If a single piece is compliant, it can be consolidated — Wrong. This is the most critical misconception this article aims to dispel.
- Misconception 5: Consolidating shipments in a consolidated container saves costs — Not necessarily. The cost of forcing a violation by consolidating shipments far exceeds the cost of booking an additional ULD.
- Misconception 6: Checking compatibility once is enough — Wrong. Every time a consolidated shipment manifest changes (adding, removing, or replacing cargo), you must go through the matrix again.
- Misconception 7: Ground handling staff will catch any issues, so you don’t need to check — Wrong. Ground handling staff only perform a final review; if they reject the shipment, the entire shipment will have to be reprocessed.
- Misconception 8: Compatibility checks can be ignored for Y-marked restricted cargo —— Wrong. Although documentation is simplified for restricted cargo, it is still subject to compatibility constraints (refer to the current DGR for specifics).
XII. Practical Checklist (60 seconds before LCL consolidation)
- [ ] List all UN numbers + main classes + subclasses
- [ ] Check Table 9.3.A matrix for each pair of combinations
- [ ] Identify all “X” combinations that cannot be packed together
- [ ] Mark all “Y” combinations requiring separation and assess the feasibility of separation
- [ ] Class 1 in a separate ULD
- [ ] Separate Class 7 items by radiation level
- [ ] Number of lithium batteries within the single ULD limit
- [ ] CAO cargo must be loaded only into CAO ULDs
- [ ] Total net weight within the ULD does not exceed the load capacity
- [ ] Secondary verification with the operating carrier’s OV
- [ ] Generate a mock loading list + two-person review
13. Method for Determining Category 3 Positions
| Position | Matrix Decision-Making Key Actions | Output |
| Freight Forwarder / Operations | Review the matrix before dispatching + Generate simulated load planning + Verify with the airline | Compliant Consolidation Plan |
| Cross-Border E-Commerce Operations | When shipping multiple SKUs, clarify combinations with the freight forwarder in advance | Logistics Solution Selection |
| Airline Loading Planner | Final Verification of ULDs and Cargo Hold Layout Before Loading | Loading Permit |
A word of advice for e-commerce operations: Many sellers assume that “compliance is the freight forwarder’s responsibility.”That’s true in the short term, but not in the long run. Once the freight forwarder you’re working with changes staff or management, and the new forwarder isn’t familiar with your product categories, problems will surface. The safest approach is to build your own basic understanding of compliance—at the very least, know the UN numbers and classes for the SKUs you’re shipping—so you can assess whether the solutions proposed by the freight forwarder during the quote phase are reliable.
XIV. Compliance and Boundary Reminders
- This article is a practical guide based on the publicly available IATA DGR Chapter 9, Table 9.3.A, and does not constitute legal, compliance, or safety advice
- The specific codes in Table 9.3.A are subject to the current version of the IATA DGR
- Individual carriers’ Operational Varies (OV) may be stricter than the matrix; check the latest version before shipment.
- Civil aviation authorities in some countries have supplementary regulations (e.g., additional distance requirements for radioactive materials and explosives).
- For complex consolidated shipments involving multiple UN numbers, it is recommended that a senior operator with DG certification or an airline load planner conduct the final review
XV. Cross-Reference with the IMDG Code for Ocean Transport
Many freight forwarding clients utilize multimodal transport—such as a combination of air and ocean freight, or road and air freight. In such scenarios, the compatibility matrix may not be entirely consistent across different modes:
| Mode | Where to Find the Compatibility Matrix | Key Differences |
| Air | IATA DGR Chapter 9, Table 9.3.A | Two-dimensional matrix by Class |
| Marine Transport | IMDG Code Segregation Table | Based on 4 segregation levels (Away from / Separated from / Separated by a complete compartment from / Separated longitudinally by an intervening complete compartment or hold from) |
| Road Transport (ADR) | ADR Chapter 7 | Handled according to 13 Compatibility Groups |
Practical Guidelines:
- For a single shipment using combined sea-air transport, the air segment must comply with IATA Table 9.3.A, and the sea segment must comply with the IMDG Segregation Table; both sets of requirements must be met
- The IMDG segregation levels are more granular than those of IATA; some combinations are permitted for ocean transport but prohibited for air transport
- The “less-than-container load (LCL) consolidation + air cargo consolidation” combination in cross-border e-commerce presents the highest level of compliance complexity
Understanding these differences will help you provide clients with more precise multimodal transport compliance advice and avoid being misled by the judgments of your ocean freight colleagues.
XVI. Conclusion: The Compatibility Matrix Is the “Invisible Baton” in the DG Chain
Unlike PI packaging or DGD labels, which appear directly on outer packaging and documents, the compatibility matrix is the most important invisible constraint throughout the entire DG supply chain. Behind every decision to consolidate a container, every ULD loading, and every flight load planning, this table is quietly scrutinizing the process.
The biggest mistake newcomers make isn’t “forgetting to check this table,” but “forgetting it even exists.” When a customer asks, “Can you load a container with consolidated cargo?” a seasoned freight forwarder’s first reaction is “List the UN numbers and run them through the matrix,” while a newcomer’s reaction is “Calculate the packing volume first.”This difference in mindset accounts for 90% of LCL mishaps.
Develop this habit: Whenever you receive an inquiry about a DG LCL shipment, first list the UN numbers and run them through the matrix before discussing pricing. This is the “professional instinct” of a DG freight forwarder. To turn this from “knowledge” into a “reflex,” you don’t need to read more documents—you need to practice it repeatedly in real-world operations.I recommend that new hires, during their first three months on the job, manually create a mock stowage plan for every DG LCL shipment they handle and have a senior colleague review it. After three months, both your speed and accuracy will reach a whole new level.
In the next post, we’ll continue with: A Quick Reference Guide to SHC Special Handling Codes (RLI / RLM / RFL / ICE, etc.) and Their Meanings—this code system serves as a “secret language” among airlines, ground handlers, and freight forwarders. Understanding it will boost your communication efficiency with ground handlers by an order of magnitude. See you next time.