Five stages, in the order they are actually performed: check the ULD, plan the stack, fix the tie-downs, net it, then re-check before it moves. Each stage has a fail state you cannot recover from later by adding strap.
| Stage | What is decided here | Failure mode |
|---|---|---|
| 1. ULD airworthiness | Frame, wheels, fittings and net condition before any cargo goes on | A damaged fitting cannot take load; you find out when the build shifts |
| 2. Stack plan | Heaviest low, centre of gravity near the centreline, contour respected at every level | Top-heavy builds pass the height check and fail the taper |
| 3. Tie-down scheme | Strap count, angle and fitting spacing against the load’s shape | Straps at a shallow angle provide little downward restraint |
| 4. Netting | Net tension, fitting engagement, coverage of the whole profile | A net that does not engage every fitting is not a restraint |
| 5. Completion check | Final contour, weight, and documentation before release | Discovered after the ULD leaves the position |
| Rule | Value | Source grade |
|---|---|---|
| Strap angle to the deck | 30° or less | Traceable to civil-aviation training material |
| Spacing between same-direction fittings | 50 cm minimum | Traceable to civil-aviation training material |
| Individual piece needing its own tie-down | 150 kg and above | Traceable to civil-aviation training material |
| Straps providing upward restraint | 2 minimum | Terminal or carrier house standard — no public regulatory source |
| Straps on one fitting | 3 maximum | Terminal or carrier house standard — no public regulatory source |
| Stacking layers for cans and drums | 2 maximum | Terminal or carrier house standard — no public regulatory source |
| Foam as dunnage | Not permitted | Terminal or carrier house standard — no public regulatory source |
| Building up on the ground | Not permitted | Terminal or carrier house standard — no public regulatory source |
| Lateral centre-of-gravity offset | 5 cm (conservative default) | Conservative default adopted by this tool |
Nets are rated by breaking strength of the lacing and the fittings, not by appearance. The relevant national standard for net assemblies gives double-tail buckle breaking strength of at least 17,800 N with mesh no larger than 254 × 254 mm. Nets exist to contain shift, not to carry the load: if the build would slide without a net, the stack plan is the problem.
Keep the combined centre of gravity near the pallet’s lateral and longitudinal centreline. The 5 cm lateral figure used by this tool is a conservative default — secondary training material also gives ±10 cm, and the binding number is the position and airframe limit in the carrier’s manual, which is lower on some aircraft. Heavy pieces on an overhang are separately forbidden on the A330 and 787 in the house standard recorded here.
Work through the steps in the simulatorPlace cargo, apply the contour, and get the completion checklist against the actual build.