Special loads, or “unusual shipments,” are cargo items that require additional tie-downs, lashing, or strapping to ensure they are secure during transportation. The equipment used for securing these items will depend on the type of cargo being transported, its weight, and the capacity of the equipment being used.
When securing cargo on an aircraft, it is important to consider the forces that will be exerted on the cargo in flight, known as G-forces.
e.g.
If you have 5000 kg cargo and the straps used have a capacity (Breaking strain) of 2250 kg at 3.0 G.
Straps to secure against upward movement
| Cargo Weight | Capacity of the strap | Straps | Straps to secure against the upward movement | ||
|---|---|---|---|---|---|
| 5000 kg | : | 2250 | = | 2.222 | 2 |
Straps to secure forward movement
| G-Force | Cargo Weight | Cargo weight | Cargo weight +G-Force | Straps | Straps to secure against the forward movement | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1.5 G | x | 5000 | = | 7500 | 5000 | : | 7500 | = | 0.666 | = 1 |
Straps to secure backward movement
| G-Force | Cargo Weight | Cargo weight | Cargo weight +G-Force | Straps | Straps to secure against the backward movement | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1.5 G | x | 5000 | = | 7500 | 5000 | : | 7500 | = | 0.666 | = 1 |
Tie-down instructions
- Tie down straps may only be used in conjunction with double stud ring bolts
- Tie-down attachment points should be spaced evenly to allow for maximum effectiveness
- When securing cargo to pallets, the tie-down points should be a minimum of 25 cm from the corners of the pallet.
- All pallet and container restraints must be serviceable and engaged when cargo is individually restrained.
- Airlines should provide the necessary equipment for securing special loads when they are booked to fly
- The type and quantity of tie-down straps used will depend on the total weight of the cargo