Air cargo is built up into a unit load device (ULD), a pallet under a net or a container, before it is loaded on the aircraft, and broken down again at the destination terminal. Your cargo is usually tendered loose and the airline, ground handler or forwarder builds the unit. If you or your forwarder build it instead, the airline sets the rules, and the height limit includes the pallet board, net and straps. At delivery, a written complaint for damage is due within 14 days of receipt. This guide covers both ends of that process. For what each ULD type is, see Air Freight ULD Types.
Loose cargo or built-up: who builds the pallet?
There are two ways cargo reaches an aircraft.
- Loose cargo. Cartons, crates or palletised goods are delivered to the airline's cargo terminal or its handling agent, weighed and measured, and built into ULDs by the airline's side together with other shipments. This is the default for most shippers.
- Built-up (shipper-built) units. A forwarder or consolidator builds the pallet or container on its own premises and tenders it as a finished unit. The airline's documents call these shipper-built units or "BUP" (built-up pallets). They are normally only accepted under an arrangement with the airline.
Common misconception: building your own pallet does not mean you can use any pallet. In both airline guidelines used in this article the pallets and nets are the airline's equipment (an unserviceable one is returned to the airline), and every unit must pass a serviceability check before use. United Cargo's guideline says pre-built units must be built by qualified staff, and that United may reject a unit that fails its rules. Nippon Cargo Airlines (NCA) makes the agent responsible for ensuring units are "Ready for Carriage".
Why security status matters for a built unit
A unit built at a forwarder's warehouse is also a security question: has the cargo been screened or does it come from a known consignor, and was it protected from tampering afterwards? If the airline cannot accept the unit as secure cargo, it has to be screened again, which can mean breaking it down. The rules differ by country and are covered in Air Cargo Security: ACAS, Screening and Known Consignor Status.
How cargo is built up onto a pallet, step by step
The steps below follow the build-up guidelines published by United Cargo and Nippon Cargo Airlines (NCA, July 2024 edition). Airlines differ in detail, so treat them as a pattern and confirm the carrier's own document.
- Weigh and measure each piece. Pieces are weighed and measured individually, because one over-height or overweight piece can change which aircraft the shipment can fly on.
- Check the base. Both airlines require a serviceable pallet with a legible manufacturer's (TSO) plate, and always a net.
- Heavy at the bottom, light on top. Heavy pieces go on the base and light pieces on top. United recommends a "bricklayer" pattern of interlocking layers of similar-sized pieces so the stack does not shift.
- Stay inside the contour. The load has to fit the contour of the aircraft position it will use. NCA says to check the contour with a gauge or by measurement and to measure height from the bottom of the pallet to the highest part of the cargo.
- Strap, then net. Both airlines treat the cargo net as the primary restraint and straps as supplementary. NCA applies tie-downs to fully restrain heavy or unstable cargo before the net goes on.
- Cover against moisture. Both airlines describe plastic sheeting under and over the load. Perishables that need ventilation are an exception.
- Label and document. The unit carries its own identification and the shipment's air waybill details, covered below.
For wrapping and strapping technique on the pieces themselves, see Stretch Wrap, Strapping and Getting a Pallet to Arrive Intact.
Height, contour and weight: why they change your rate
Air freight is normally priced on chargeable weight, the greater of actual and volumetric weight (see How Air Freight Pricing Works). Pallet limits matter on top of that because they decide which aircraft and which deck the cargo can use, and a freighter flies less often than a passenger belly on many routes. Some forwarders also buy space by the whole ULD rather than by the kilo, so a poorly filled unit can cost the same as a full one.
Do not copy a height figure from a generic chart. The limits belong to the airline, aircraft type and deck. Two airlines' own published guidelines show how far apart they can be:
| Item | United Cargo guideline | NCA guideline (July 2024) |
|---|---|---|
| Maximum height | 64 in (160 cm) for any pallet or container; pallets over it will be rejected | 299 cm (118 in) for its aircraft, shown with a Boeing 747-F contour chart |
| What the height includes | Pallet board, net and straps | Pallet board, net and tie-down straps |
| Heavy single pieces | Shoring (load spreading) typically needed for concentrated loads over 1,000 kg | Pieces over 500 kg must be notified to NCA in advance |
| Dangerous goods in shipper-built units | Prohibited, except items its guideline identifies by reference to the IATA Dangerous Goods Regulations | Listed among items that cannot be shipped as shipper-built units |
The 160 cm and 299 cm figures are not contradictory: they are different airlines and fleets, and NCA's chart separates main-deck contours (IATA height codes Q6 and Q7) from a lower-deck contour. A piece that is fine on a main-deck position may not fit a lower-deck one, which is how a single over-height piece can force a shipment off a passenger flight and onto a freighter. The types and codes behind these numbers are in Air Cargo ULD Types and Dimensions.
Weight is limited per ULD type too. NCA's chart for its 747 freighters lists 1,588 kg maximum gross for an AKE container and 6,800 kg for a PMC pallet. United also notes that some AKE containers carry a "not approved for 787" sticker, so even a standard unit type is aircraft-specific.
Documents that travel with a built-up unit
A built-up unit does not replace the air waybill; it adds a layer of record-keeping on top of it.
- Air waybill (AWB). Still one per shipment. See Air Waybill Explained for master and house documents.
- Build-up sheet or ULD manifest. United says there is no standardised form, but asks that a build-up sheet show each ULD, the house air waybills by ULD and the pieces by house air waybill, particularly when several units and several house bills are tendered together. Without it, a customs hold or examination can delay the shipment at destination.
- Security status. The unit's screening or known-consignor status, as above.
- ULD Control Receipt (UCR). This is not a cargo document. IATA's ULD Regulations include a receipt, based on IATA Recommended Practice 1654, that records the transfer of a ULD (the equipment) between an airline and another party such as a handler. A shipper normally never sees one, and it is not proof of how your cargo was packed.
The load plan, which says which aircraft position each unit takes, is prepared by the airline for weight and balance, not by the shipper.
What happens at breakdown at the destination
When the aircraft lands, units are taken to the airline's or handler's cargo terminal. The unit is broken down: the net comes off and the cargo is separated by air waybill. Each shipment is then typically held, often in what is called the import shed or import warehouse, until customs release and delivery arrangements are complete. Two practical points follow.
- Breakdown is where hidden damage appears. NCA's guideline says long and narrow cargo must be built so it does not collapse when other cargo is removed during breakdown, which is the moment a poorly restrained piece falls.
Damage, shortage and overage: reporting and claim deadlines
When cargo is delivered, the consignee (the person entitled to delivery) holds the clock, so make sure whoever collects knows what to check.
Name of the report. The short answer to "what is a CIR" is that the name varies. IATA's own cargo handbook for the European air cargo programme says the carrier or its handling agent has to issue a Cargo Damage Report (CDR) on request at delivery. Many handlers and airlines call the same thing a cargo irregularity report, an irregularity report or a CIR. Ask for it by description and confirm what the airport calls it.
| Problem | Written complaint due | Source |
|---|---|---|
| Damage to cargo | Forthwith after discovery, and at the latest within 14 days from the date of receipt | Montreal Convention Art. 31; IATA Resolution 600b clause 10.1.1 |
| Delay | Within 21 days from the date the cargo was placed at the consignee's disposal | Montreal Convention Art. 31; Resolution 600b clause 10.1.2 |
| Non-delivery | Within 120 days from the date of issue of the air waybill | Resolution 600b clause 10.1.3 |
| Court action | Within two years of arrival, or of the date the aircraft ought to have arrived, or of when the carriage stopped | Montreal Convention Art. 35; Resolution 600b clause 10.4 |
These are as of November 2026 and apply where the Montreal Convention or the air waybill conditions govern the carriage. IATA's handbook notes that in some countries other conventions apply and that some airlines require registered mail, so check the reverse of your air waybill and the airline's conditions. Three details catch shippers out:
- Receipt without complaint is prima facie evidence that the cargo arrived in good condition (Montreal Convention Art. 31(1)). Note visible damage on the delivery receipt, do not sign it clean, and photograph the cargo, the unit and the net before it is separated.
- The complaint must be in writing. A phone call to the handler does not count. Under Art. 31(4), if no complaint is made in time, no action lies against the carrier except in cases of fraud.
- Packing is your side of the line. The Convention's Article 18(2)(b) excludes liability for defective packing of the cargo performed by a person other than the carrier or its servants or agents. United's shipper-built waiver goes further: if it flies a unit that does not meet its rules, it disclaims liability for cargo loss on that unit. A shipper-built unit therefore moves risk onto whoever built it.
The amount you can recover is capped by the carrier's liability limit unless you declared a higher value for carriage, which is explained in Carrier Liability Limits. The filing sequence is in How to File a Cargo Claim. Per IATA's handbook, evidence typically includes a copy of the air waybill, the Cargo Damage Report and invoices.
How to reduce cost and damage
- Give piece dimensions and weights, not just totals, at booking. One over-height piece can change the aircraft.
- Right-size the pallet. Build to the height of the deck you are buying, remembering the board, net and straps count towards it.
- Put heavy and dense pieces at the base and interlock the layers. Keep tall, narrow pieces from standing alone.
- Keep dangerous goods out of mixed units. Both airlines restrict them in shipper-built units, so declare dangerous goods separately to your forwarder in advance.
- Protect against moisture, and use clear wrap where the airline prefers it so it can inspect the build.
- Agree who photographs the unit at build and at breakdown.
What to do next
- Ask your forwarder whether your cargo will be tendered loose or as a shipper-built unit, and who carries the build risk.
- Get the airline's current height, contour and weight limits for the flights you are using, in writing, and measure with the pallet board and net included.
- Ask for a build-up sheet by ULD and house air waybill, and for the security status of any built unit.
- Brief your consignee on the clocks: photograph and note damage at delivery, ask for the Cargo Damage Report, and send written notice within 14 days.
More than 29,300 logistics companies are searchable by country and service in the CargoLinked directory, and the public requests board lists freight that shippers have posted for forwarders to quote on directly. Ask each forwarder you speak to how they handle build-up and what they do when a unit arrives damaged.
This article is general information, not legal or insurance advice. Airline guidelines were read from their published documents (United Cargo's Shipper Built Unit Guidelines; NCA's guideline dated 12 July 2024) and may have changed; the Convention and IATA text is as quoted from their published versions. Confirm limits, time limits and procedures with the airline, handler and a licensed professional.
