Air cargo reliability dropped sharply in 2025. The Delivery As Promised score tracked by CargoAi fell to 62.7 percent for the year. Tariff changes, network realignments, and peak season pressure drove most of that decline. Domestic parcel carriers told a different story in the same period. USPS, FedEx, and UPS hit between 94 and 97 percent on-time delivery in December, according to ShipMatrix.
That contrast matters for any US brand shipping abroad. Your domestic network may look healthy in November. Your international lanes, however, run on air capacity, destination customs, and foreign last mile carriers. Those pieces behave very differently under peak volume.
The delivery time shown at checkout usually comes from a historical average. That average rarely reflects what happens when peak volume, rerouted air capacity, and overloaded customs all hit at once. Unfortunately, that combination describes exactly the weeks that matter most.
Why the checkout SLA carries a number that is no longer true
Every delivery estimate in your checkout comes from somewhere. Typically, it reflects average transit time measured across a normal period. In November, that average breaks for three reasons working together.
First, carrier capacity tightens. As we covered in our breakdown of why Black Friday is your operation’s biggest stress test, cross border order volume grows faster than domestic volume during peak. That demand competes for space in networks that do not scale at the same rate.
Second, destination customs runs above normal capacity. That alone adds days to transit. Third, and specific to recent years, tariff changes force carriers to reroute international lanes. CargoAi names that exact factor as the main cause of the 2025 reliability drop.
An SLA built without these three pressures is not optimistic. Instead, it is a number that was already outdated for the one week when accuracy matters most.
What destination customs does to delivery time in November
International shipments already carry wider delivery windows than domestic ones. In November, those windows stretch further. Moreover, the stretch is not uniform across destinations or product categories.
A bundle with mixed components feels the delay first. So does a product with ambiguous classification, or a shipment with incomplete customs data. A single SLA applied across the entire catalog hides that difference. It treats a simple product and a complex one as if they carried the same delay risk. In reality, they do not.
The EU and UK add another layer. Low value parcels now face stricter customs data requirements in both markets. Consequently, a shipment that cleared quickly in spring can sit longer in November, simply because customs processes more entries per day.
Why widening the delivery window is discipline, not pessimism
Experienced retailers do the same thing every year. They deliberately widen the promised delivery window during peak. This is not a lack of confidence in the operation. Rather, it reflects a simple fact. Promising a normal month’s delivery time during peak is one of the most common mistakes an unprepared operation makes.
A wider window protects two things at once. It protects the customer from an expectation the operation cannot meet. It also protects support from a flood of order status questions. During the Black Friday Cyber Monday weekend, that contact volume can reach three to five times normal levels. A realistic SLA, even a longer one, generates fewer tickets than an optimistic SLA that breaks.
The peak surcharge carriers already announced, and what it signals about time
FedEx and UPS publish peak demand surcharges months in advance. Each surcharge carries a specific amount per package type and a defined window. The common mistake is not ignoring these surcharges. Instead, teams treat them purely as a cost problem.
In practice, peak surcharges and delivery delays come from the same source, which is contested network capacity. A surcharge on oversize or additional handling packages signals that those shipments consume more network resources during that window. Therefore, a brand that pays the surcharge but ignores the signal in its delivery estimate keeps publishing an SLA that no longer matches reality.
What changes when delivery time and cost live in the same calculation
Delivery time and freight cost look like separate variables. In November, however, both come from the real capacity of a specific lane in a specific week. When one system calculates cost and another publishes the checkout SLA, the SLA ends up too optimistic. Neither system sees the signal the other already captured.
That is why centralizing landed cost, peak surcharge exposure, and delivery estimates in one operating layer changes the outcome. The same data then feeds both the price and the promise. As a result, the brand adjusts both together, instead of discovering the gap after the order is placed. We explained the same single-source logic, applied to pricing, in our guide to import management software categories in 2026. The principle holds exactly the same for delivery time.
What to adjust before publishing your November SLA
Review the SLA by destination and by product category, not as one number for the whole catalog. A simple product going to a fast-clearing market can keep a shorter promise. A complex product, or a historically slow destination, needs a wider window.
Next, confirm real peak capacity with each carrier, not the nominal capacity in a contract signed off-season. Then adjust order cutoff times for fulfillment and dispatch, since your warehouse also runs at higher volume in November. Finally, show the revised delivery window clearly at checkout before peak begins. That way, the customer buys already knowing what to expect.
ShipSmart connects landed cost calculation, peak surcharge exposure, and real delivery time by destination into one flow. The SLA in your checkout stays true in November. Book a Black Friday readiness call and review your delivery promise before peak arrives.
