Unit Load Device (ULD)

A Unit Load Device (ULD) is either an aircraft pallet and pallet net combination, or an aircraft container. It allows preloading of cargo, provided the containerised load fits in the aircraft, enabling efficient planning of aircraft weight and balance and reduced labour and time in loading aircraft holds compared with 'bulk-loading' single items of cargo or luggage by hand. ULDs are removable aircraft parts subject to strict civil aviation authorities' requirements from design, testing, production, and operations, to repair and maintenance. An airworthy ULD must be structurally capable of restraining the loads and providing adequate protection to the aircraft systems and structure during flight. All ULDs are identified by their ULD number: a three-letter prefix identifies its type and key characteristics, followed by a 4 or 5 digit serial number to uniquely identify it from others of the same type, and ending with a two character suffix identifying the ULD's owner (if an airline, often the same as IATA designator codes).

An American Airlines LD-3 container bears the ULD number AKE 45789 AA, where AKE identifies it as a contoured container, 45789 is the unique serial number, and AA designates American Airlines as the owner. A Lufthansa Cargo pallet displays PMC 67234 LH, indicating a certified main deck pallet (PMC) with serial number 67234 owned by Lufthansa Cargo (LH).

• ULD
• air cargo container
• airline container
• aircraft pallet
• air freight container

What do the letters in a ULD identification code mean?

The first 3 letters define the physical characteristics of the ULD. Position 1 defines the category (A for certified container, P for certified pallet, R for thermal certified container), position 2 describes the base dimensions of the unit, and position 3 describes the container's contour or the pallet's restraint system classification.

How many ULD positions can a Boeing 777 cargo hold accommodate?

Each half-width container (LD1/LD2/LD3) occupies one position, with typically each row in a cargo compartment consisting of two positions. Therefore, a full-width container (LD6/LD8/LD11) takes two positions. For Boeing 777 lower hold, LD-6 containers are suitable with maximum gross weight of 3,175 kg (7,000 lb).