Identifying a Unit Load Device (ULD)

Each Aircraft Unit Load Device (ULD) is identified by its ULD code. This code is a unique combination of letters and numbers, starting with a three-letter prefix that indentifies the type of ULD. This prefix is followed by a unique 4 or 5-digit serial number to distinguish it from others of the same type. The last two or three characters designate the owner of the ULD (e.g. the airline).

Many different parties handle ULDs as they pass between airlines and airports around the world, so a system was needed to identify easily and quickly each ULD. Therefore, the International Air Transport Association (IATA) introduced a global standard system of identification. Accordingly, each ULD is assigned a unique ULD code, which is clearly visible on the relevant unit. By standardising the system, all manufacturers, cargo handlers and airlines can now identify the ULD’s classification and the owner at a glance.


The first three letters of a ULD code are perhaps the most important. They are used to identify the type, size and shape of the ULD. This information is vital in determining not only the type of cargo it can contain but also the aircraft it is compatible with.

The three-letter prefix works as follows:

  1. The first letter represents the type of ULD
  2. The second letter represents the base size of the ULD
  3. The third letter represents the container’s contour or the pallet’s restraint system

ULD Categories

At VRR, we love to experiment and to challenge the status quo. That’s because we want to make unique products that help overcome real world challenges in the air freight industry. Our ambition to be curious, courageous and uncompromising has led to six distinct families of customised cargo solutions:

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