Air freight is faster and much more expensive per kilogram than sea. The decision is therefore a business calculation, and it depends on who is responsible for the delay and what you agreed in the contract. Do the calculation with real quotes before agreeing anything.

Work out the cost per unit

Ask a forwarder for an air quote for the actual cartons and weights, and divide by units. Add the other costs of the faster mode, such as handling at origin and destination. Compare cost per unit with your gross margin per unit. If the air cost per unit is larger than the margin on the units, shipping all of them by air loses money on each, unless it saves a sale that would otherwise be lost.

Consider a split

A common middle path is to send part of the order by air, perhaps the best-selling styles, sizes and colours or those tied to a campaign, and the rest by sea. That protects the sales that matter most for a smaller cost. Decide the split from sales data, not from what is easiest to pack.

Who should pay

The ICC explains that Incoterms rules deal with delivery, the transfer of risk and who bears certain costs, and that they do not deal with the consequences of a breach of contract. Late production is a matter for the sales contract or PO, not the trade term. If you set delay remedies such as a discount or the supplier paying for air freight when late, use them. If not, negotiate: ask the factory to pay all or part of the air premium, given that the delay is theirs.

Check the paperwork

A change of mode means new documents, a new booking and a new customs entry. Make sure the commercial invoice and packing list match the shipment actually moving, and your broker has them before arrival. CBP’s guidance notes that the importer is responsible for reasonable care in entering goods.

Record the decision

Write down the agreed split, who pays what and the new dates, and keep it with the PO. Review the lead time on the next order.