The early days of air cargo did not involve containerization – all cargo was handled in bulk. ULDs were introduced with the advent of wide-bodied aircraft in the early 1970s. Since then, ULD have become indispensable to the efficient movement of air cargo and baggage around the world with a current estimated global fleet of 900,000 units1.
As ULD usage grew, it quickly became apparent that transferring these assets between airlines was inevitable. At that time, a number of airlines formed a special interest group under IATA to develop a set of rules for the exchange of ULDs in the course of cargo interlining. This group put together a set of rules, the “ULD Control Manual,” and subsequently created the necessary IT system running on the IATA mainframe in Montréal. This system provided the airline industry with a way to record interline transfers and calculate the demurrage when units were returned beyond the five-day free period. It is called the Interline Unit Load Device User Group (IULDUG).