ISO 21100:2025

Overview

ISO 21100:2025 - "Air cargo unit load devices - Performance requirements and test parameters" is an international standard that defines minimum airworthiness requirements and test parameters for air cargo unit load devices (ULDs): pallets, nets and containers. Intended as a uniform technical reference for ULD airworthiness approval, the standard applies to ULDs carried on civil transport airplanes certificated under CCAR 25, EASA CS‑25 or 14 CFR Part 25 (or equivalent). ISO 21100:2025 is the third edition and adds T and U sizes and associated restraint conditions.

Key topics and technical requirements

• Scope and applicability: Covers ULDs requiring airworthiness approval for installation in approved aircraft cargo compartments and restraint systems. Presupposes compliance with applicable civil aviation regulations and the aircraft manufacturer’s approved Weight and Balance Manual.
• Performance requirements: Minimum requirements for materials, fabrication, protection, construction, marking, inspection, fire protection, rapid decompression, dimensions/tolerances and strength.
• Strength and restraint: Defines ultimate load criteria, restraint criteria and base performance for pallets, nets and containers, including environmental degradation considerations.
• Test parameters: Specifies test requirements, parameters and how results are reported (test methods are referenced but detailed proprietary test procedures and some operational methods are outside scope).
• Classification and configurations: Classifies ULDs by type, size, configuration and form; provides detailed configuration definitions (A7, A8, B7, B8, G1, K4, L5, etc.) and associated restraint conditions.
• Restraint conditions: Details multiple restraint conditions (RC A1, A2, G, K, L, N, P, Q, R, T, U) for testing ULD restraint performance.
• Units and notation: Dimensions in millimetres (inches shown in brackets), forces in newtons (pound‑force shown in brackets).

Note: ISO 21100:2025 exclusively addresses ULD airworthiness approval and testing parameters. It does not cover aircraft design, operational requirements, detailed ULD design specifications, in‑service damage limits, load distribution models, CG control means, or utilization guidelines.

Practical applications - who uses this standard

• Airlines and cargo operators for ULD procurement and airworthiness compliance
• ULD manufacturers and fabricators for certification preparation
• Aircraft manufacturers and weight & balance engineers to ensure compatibility with cargo restraint systems
• Certification authorities and •airworthiness approval• organizations assessing ULD compliance
• Test laboratories performing ULD performance validation and reporting

Related standards and references

• CCAR 25, EASA CS‑25, 14 CFR Part 25 (transport category airplane certification)
• ICAO Annex 8 (Airworthiness of aircraft)
• ISO/TC 20/SC 9 (technical committee responsible for air cargo and ground equipment)

Keywords: ISO 21100:2025, air cargo unit load devices, ULD, airworthiness, performance requirements, test parameters, cargo restraint, pallets, containers, nets.