2026 Air Freight ULD Complete Guide

1. ULD Definition & Core Classification

A Unit Load Device (ULD) is a standardised container or pallet used in air cargo to consolidate freight, baggage, and mail for efficient loading and safe transport. All ULDs fall into two primary categories: containers and pallets.

1.1 Structural Classification

Type	Structure	Advantages	Disadvantages
Container	Enclosed rigid shell (aluminium/fibreglass), with door, locks; some insulated	Strong protection (waterproof, dustproof, tamper-resistant); ideal for fragile/valuable cargo	Higher tare weight reduces payload; less flexible loading
Pallet + Net	Flat aluminium/composite base with rope net or tarpaulin to secure cargo	Lightweight, flexible; accommodates oversized or irregular cargo	Weaker environmental protection; requires strict securing

1.2 IATA Standard Codes (Main Types)

IATA standardises ULDs by dimensions and compatible aircraft type:

2. Temperature & Humidity Controlled ULD (Cold Chain)

Temperature-controlled ULDs are the backbone of air cold-chain logistics. They divide into active and passive systems; premium models integrate humidity control (40%–60% RH), real-time monitoring, and alarms.

2.1 Active Temperature-Controlled ULD

Self-contained mechanical refrigeration/heating, battery-powered. Precise temperature control −30°C to +30°C, humidity adjustment, battery life ≥ 30 hours — suited for long-haul cross-border cold chain.

2.2 Passive Temperature-Controlled ULD

No active refrigeration. Relies on dry ice, gel packs, coolants + high-density insulation. Lower cost, shorter endurance (8–12 hours) — suitable for short-haul cold chain.

• AKE Reefer (LD2 Passive): +2°C to +8°C (chilled) / −18°C (frozen); widebody lower deck; fruits, vegetables, flowers, standard seafood
• Insulated Container: Insulation layer + coolant only, ±3°C deviation; non-sensitive chilled cargo, short transit

2.3 Temperature/Humidity Controlled ULD — Comparison

Model	Type	Temp Range	Humidity	Endurance	Compatible Aircraft
RKN	Active	−20°C to +25°C	40%–60% RH	≥ 30 h	B777 / B787 / A330 / A350
RAP	Active	−18°C to +30°C	Controllable	≥ 30 h	B747 / B777F / A380F
AKE Reefer	Passive (dry ice)	+2°C to +8°C / −18°C	None	8–12 h	Widebody lower deck
Insulated	Passive (gel)	±3°C deviation	None	6–8 h	All types

3. Aircraft Type Compatibility Reference

ULD compatibility is strictly constrained by hold dimensions, weight limits, and door openings. Widebody and freighter aircraft offer the best compatibility; narrowbodies only accept small ULDs.

3.1 Widebody Passenger Aircraft (Main / Lower Deck)

Aircraft	Compatible ULD Types	Notes
B777 / B787	RKN, AKE, LD3, PMC pallet, P1P pallet	Twin-aisle widebody, large hold volume
A330 / A350	RKN, AKE, LD3, PMC pallet	Main + lower deck dual-level loading
A380	RKN, RAP, full-size pallets	Extra-large lower hold; accommodates RAP active

3.2 Freighter Aircraft (Main Deck)

Aircraft	Compatible ULD Types	Notes
B747F	RAP, ALF, PGA super pallet, PMC, all container types	Primary freighter — upper + lower main decks
B777F	RAP, RKN, LD3, PMC pallet	High-capacity freighter, 2×3 pallet layout
A330F	RKN, LD3, P1P pallet	Mid-size freighter; supports cold-chain RKN

3.3 Narrowbody Aircraft (B737 / A320 Family)

4. Cargo Suitability by Temperature Requirement

Cargo Type	Temp Requirement	Humidity Requirement	Recommended ULD
Vaccines, biologics, monoclonal antibodies	+2°C to +8°C / −20°C	40%–60% RH	RKN Active
Blood products, stem cells, biological samples	−18°C to +4°C	45%–65% RH	RKN / RAP Active
Premium seafood (salmon, lobster)	0°C to +4°C	50%–70% RH	RAP Active / AKE Passive
Fruit, vegetables, cut flowers	+2°C to +15°C	60%–80% RH	AKE Reefer
Frozen food, meat	Below −18°C	No strict requirement	RAP Active / AKE Passive
Precision electronics, semiconductors	+15°C to +25°C	40%–50% RH	RKN Active
Cosmetics, health supplements	+10°C to +25°C	40%–60% RH	Insulated / AKE
Live animals (pets, livestock)	+15°C to +24°C	50%–70% RH	AVI Animal Container

5. Dangerous Goods Loading Rules (IATA DGR)

Air transport of dangerous goods must comply strictly with the IATA Dangerous Goods Regulations (DGR, 67th Edition 2026) and ICAO Technical Instructions. Five core principles govern ULD usage for DG cargo: Dedicated ULD · Segregation · Securing · Labelling · Documentation.

5.1 ULD Qualification & Selection Requirements

• Only ULDs compliant with IATA standards, inspected and bearing valid airworthiness tags may be used. Damaged, deformed, or defective ULDs are strictly prohibited.
• DG cargo must use enclosed rigid containers (LD3, LD9, RKN, etc.). Open pallets + nets are prohibited for liquids, leakage-prone, toxic, or radioactive goods.
• Explosives, radioactive materials, and infectious substances require dedicated DG ULDs (DG markings, reinforced structure, anti-static properties).
• Lithium batteries (UN3480 / UN3556) require fire-resistant, anti-static, short-circuit-proof dedicated ULDs — must not be co-loaded with liquids or acidic substances.

5.2 Loading & Securing Mandatory Standards

• Individual and total weights must not exceed ULD and aircraft limits; centre of gravity centred — single-point overload and off-centre loading are prohibited.
• DG packages must be intact with clear labels and correct UN numbers — leaking, damaged, or illegible packages must not be loaded.
• All cargo inside must be fully secured (straps, cushioning, dividers) to prevent shifting, collision, or inversion.
• Liquid DG must be loaded upright, closures facing up, with a leak-proof tray underneath.
• Organic peroxides and self-reactive substances must be kept away from heat sources, protected from light, and ventilated — never tightly sealed.

5.3 DG Segregation & Incompatibility Rules

Segregation Category	Requirement	Typical Forbidden Combinations
Different DG classes	Incompatible classes must be fully segregated (different ULDs / holds)	Flammable liquid + oxidiser; strong acid + strong base; toxic + food
DG vs. general cargo	Minimum 1-metre gap or physical barrier; food, medicine, live animals — no co-loading	DG + fresh produce / pharmaceuticals / pets
Radioactive materials	Class II/III Yellow-label must use dedicated ULD, segregated from personnel and photographic film	Radioactive + photographic film / medical supplies
Lithium batteries	Must not share ULD with flammable liquids, compressed gases, or corrosives	Lithium battery + paint + gas cylinder

5.4 Marking & Documentation Requirements

• ULD exterior must display: DG hazard labels (orange diamond), UN number, hazard class, handling warnings.
• Mandatory accompanying documents: Dangerous Goods Declaration (DGD), Air Waybill (AWB), Packaging Test Certificate, Emergency Response Procedures (ERP).
• ULD load record must state: UN number, class, quantity, emergency contact number.

5.5 Absolutely Prohibited Items (No ULD, No Air Transport)

6. Summary & Industry Trends

The ULD ecosystem — containers and pallets — forms the infrastructure of modern air freight. Temperature-controlled ULDs (RKN / RAP / AKE) are the critical enablers of air cold-chain logistics: active systems serve high-value pharma and premium fresh cargo; passive systems cover standard chilled shipments. For dangerous goods, strict use of dedicated ULDs, rigorous segregation, proper securing, complete labelling, and full documentation are non-negotiable under IATA DGR.

Key trends: Active temperature control + IoT real-time monitoring + extended battery life; improved humidity precision; lightweight materials reducing tare weight. DG-specific ULDs are evolving toward fire-resistance, explosion-proof design, anti-leak features, and intelligent monitoring to accommodate broader cargo types and aircraft.

7. Ginga Logistics Air Freight DG Services

Shanghai Ginga International Freight Forwarding Co., Ltd. holds Class A freight forwarder certification and has served clients in the chemical, pharmaceutical, and new energy sectors with full-service dangerous goods air freight solutions for over a decade: