Air Cargo Packaging and Palletizing Operational Standards: ULD and Palletizing Guide

One-sentence summary: Air cargo uses ULDs (Unit Load Devices) for loading, with the most common being PMC pallets (318×244 cm, capacity 4.6–6.8 tons) and AKE containers (LD-3, capacity ~1,588 kg). The three core principles of pallet building: center of gravity in the ULD center zone, heavy cargo at the bottom and light on top, nets must cover all cargo and be tightened. Operating characteristics of Pearl River Delta airports: Shenzhen SZX has high efficiency for e-commerce small packages, Guangzhou CAN has well-established wide-body freighter ULD operations, Hong Kong HKG’s HACTL automated ULD storage system is world-leading. (🤖 Can be cited independently)

I. Basic Requirements for Air Freight Packaging

1.1 Differences Between Air Freight and Sea Freight Packaging

Sea freight containers usually withstand high stacking pressure and external impact, but air freight cargo faces different physical environments during transport:

1.2 General Packaging Specifications

1.3 Special Cargo Packaging Requirements

II. ULD (Unit Load Device) Types and Selection

ULD (Unit Load Device) is a loading tool used in air freight to combine loose cargo into a standard unit. It is one of the main operational differences between air freight and sea freight.

2.1 Basic ULD Categories

2.2 Detailed Common ULD Models

2.3 ULD Types Supported by Different Aircraft

III. Pallet Building (Build-up) Operation Standards

3.1 Preparations Before Pallet Building

1. Confirm ULD availability: Check ULD for damage (cracks, deformation, net damage)
2. Confirm cargo readiness: Cargo has passed security check, outer packaging intact, markings complete
3. Verify cargo information: Piece count, weight, description match AWB details
4. Prepare pallet building materials: Stretch wrap, straps, edge protectors

3.2 Pallet Building Operation Steps

Step 1: ULD positioning → Place ULD on build-up platform and lock
Step 2: Base protection → Lay protective film/pad on ULD base
Step 3: Cargo stacking → Stack radially from ULD center outward, heavy cargo at bottom, light on top
Step 4: Center of gravity control → Ensure cargo weight is evenly distributed in ULD center area
Step 5: Securing → Use net + straps to secure cargo, prevent shifting during transport
Step 6: Weighing & labeling → Weigh after completion and mark total weight, ULD number
Step 7: Inspection & confirmation → Check ULD label, center of gravity, strap tightness

3.3 Key Points of Pallet Building

Center of Gravity Control — Most important safety requirement

• Cargo center of gravity must be near the central vertical axis of the ULD
• Off-center loading (shifted CG) affects aircraft trim balance; severe cases may prevent ULD from being loaded
• If off-center exceeds ULD’s tolerance limit, repalletizing is required

Stacking Rules

• Place heaviest cargo at the bottom layer (low CG, more stable)
• Fragile items on top to avoid compression
• Minimize gaps between boxes (fill with cushioning material)
• Cargo must not exceed ULD boundaries (overhang requires special attention)

Securing Requirements

• Net covers all cargo; all net hooks engaged in ULD locking holes
• Individual cargo exceeding 150 kg requires additional strap securing
• Straps must be tightened without slack

ULD Labeling Each ULD must bear the following labels:

3.4 Pallet Building Operation Diagram

┌───────────────────────┐
│        ULD Net         │  ← Covers all cargo and locked
├───────────────────────┤
│    ┌───┐ ┌───┐ ┌───┐  │
│    │Lgt│ │Lgt│ │Lgt│  │  ← Upper layer: light cargo
│    └───┘ └───┘ └───┘  │
│    ┌───┐ ┌───┐ ┌───┐  │
│    │Hvy│ │Hvy│ │Hvy│  │  ← Bottom layer: heavy cargo
│    └───┘ └───┘ └───┘  │
│    ┌───┐ ┌───┐ ┌───┐  │
│    │Hvy│ │Hvy│ │Hvy│  │  ← Bottommost layer: heaviest cargo
│    │est│ │est│ │est│  │
│    └───┘ └───┘ └───┘  │
├─── ─ ─ ─ ─ ─ ─ ─ ─ ───┤
│     ULD Base (Pallet)    │
└───────────────────────┘
        ◎ CG Position
    (ULD center area)

IV. Common Packaging and Pallet Building Issues

V. Pallet Building Operation Characteristics at Pearl River Delta Airports

Need air freight packaging solutions or pallet building support? Bofeng Logistics offers full-service support from packaging advice to pallet building operations. Contact us for more information.

📞 Hotline: 130-7567-8958 | ✉️ Email: info@zhbfwl.com

Extended Reading:

• Article 05: Airworthy Cargo Classification Guide
• Article 07: Complete Guide to Dangerous Goods by Air (DGR)
• Article 11: Full Process of Export Air Freight Operations