Asian port congestion leaves container lines a steep climb back onto schedule

Sea-Intelligence reported on Aug. 26 that global container schedule reliability fell 6.1 percentage points in one month, to 56.4% in July. Put plainly, barely more than half of the vessel arrivals it tracks came in on time.

Sea-Intelligence's August figure comes next, and if it keeps the late-month rhythm of its 2026 releases it will land within days. It will settle a question ARCANE has left open on its public track record: “Will Sea-Intelligence report global container schedule reliability below 60% for August 2026?” The evidence published since July points toward yes. Sea-Intelligence reported in its Aug. 26 and Sept. 2 releases that no carrier recorded a month-on-month improvement in July, that the average delay for late arrivals lengthened, and that every one of the busiest ports in the region it studied lost on-time arrivals. A one-month climb back over the line has happened once this year, from a far shallower dip.

A year that kept snapping back

The year opened strongly. Sea-Intelligence reported on Feb. 24 that global schedule reliability, the share of container ships arriving on schedule, stood at 62.4% in January. Sea-Intelligence then reported on March 30 that February had slipped to 59.0%, the lowest figure recorded since April 2025 and the first month this year below 60%.

After that came a year that kept snapping back. Sea-Intelligence reported on April 27 that March reliability climbed to 62.2%, a rise it put at 3.9 percentage points. Container News, summarising Sea-Intelligence's April data on Sept. 25, reported a small further gain that brought April level with January, “making this the highest figure for 2026 so far.”

The high point came in May, a month whose level has to be worked out rather than read. Sea-Intelligence reported on July 27 that June reliability dropped 1.9 percentage points to 62.6%; adding that fall back implies a May reading of about 64.5%, the best of the year. The monthly changes the firm publishes do not always match its published levels to the decimal. Its February and March levels sit 3.2 points apart, less than the gain it reported for March, so the May number here is an estimate rather than a reading.

July wiped out the year's progress in a single month. Sea-Intelligence called it, in a Sept. 2 note, the sharpest single-month decline since January 2021. Measured level to level across the firm's releases, reliability ended July 6.0 points below January and about 8.1 points below the implied May peak. July's one-month drop was larger than the whole net decline from January to July.

Not one carrier got better. Sea-Intelligence reported on Aug. 26 that no carrier recorded a month-on-month improvement in schedule reliability in July. Ships that arrived late also arrived later: the firm reported that the average delay for late vessel arrivals rose by 0.59 days in the month, to more than six days. So July's drop was not only a matter of more ships missing their arrival windows; the ones that missed were, on average, later than a month earlier.

The same two carriers keep topping the rankings. Sea-Intelligence reported on Feb. 24 that Hapag-Lloyd and Maersk were the joint-most reliable of the top 13 carriers in January, at 72.2%. Container News reported on Sept. 25 that Maersk led again in April at 76.1%, followed by Hapag-Lloyd at 75.1%, which put Maersk 13.7 points above the industry that month. At the bottom, Sea-Intelligence reported on July 27 that Wan Hai was the least reliable carrier in June, at 35.6%. Even allowing for the different months, the distance between best and worst dwarfs any swing in the industry average.

That hierarchy makes July's pattern telling. When neither the most punctual networks nor the least punctual manage a month-on-month gain, the likelier cause sits outside any one line's operations, in the ports and sea lanes they share.

Every one of the busiest ports

Sea-Intelligence's own diagnosis points to the ports. In a Sept. 2 note that tied the July drop to congestion at Asian ports, the firm reported that all 14 of the region's busiest ports saw on-time vessel arrivals decrease. Every one of the busiest ports, not a handful: that pattern fits a region-wide queue far better than an accident at a single terminal.

Delay has a physical size. In a note published on Aug. 19, Sea-Intelligence wrote that 5.0% of all global deep-sea capacity is tied up in delays, a volume it measured in TEUs, twenty-foot equivalent units, the standard measure of container space. Capacity absorbed by lateness is not available for the next scheduled departure, which suggests a bad month tends to leak into the one after it rather than ending cleanly.

The data runs behind the ships. July's slide was already over when Sea-Intelligence published its figure late in August. The same lag means the August reading will describe a month that is already finished, one that began straight after a July fall Sea-Intelligence tied in a report earlier this month to congestion at Asian ports.

The second pressure moves more slowly. Sea-Intelligence reported on Sept. 16: “The total normalisation of the Red Sea routing stands at a solid 27%”. Normalisation here is a gauge of how far carriers have returned to routing through the Red Sea. Solid is the firm's word, and it marks progress, but on that gauge most of the diversion is still in place. A return roughly a quarter complete is a slow tailwind for timekeeping, not a switch that can flip a single month's reading.

The alliance map gives only a partial answer to who could switch. Sea-Intelligence reported on Sept. 9, in a study of how the carrier alliances' networks overlap, that “65% of direct port-pairs see no overlap”, meaning most pairs of ports linked by a direct alliance service are covered by just one alliance. The same analysis found that MSC calls 40% of all single-alliance port pairs, the largest share of that specialised space. The study counts port pairs, not cargo, so it cannot say how many shippers depend on those pairs, or whether other carriers or indirect routings through a hub port could serve them.

ARCANE's public track record lists every scored Call it makes, open and resolved, each with “a probability, a resolve-by date and the exact rule that decides them.” The open August question rests on a series that can be assembled month by month from Sea-Intelligence's own releases, and assembled that way it tells a sharper story than any single release. Reliability has been below the 60% line twice this year, in February and July. February missed it by a single point; July's shortfall is more than three times as deep.

That gap sets a high bar for one month. To get back over the line, August must regain more ground than March did, measured level to level, and nearly as much as the largest monthly gain Sea-Intelligence reported this year, in its April 27 release. It can happen; it happened in the spring, from a smaller hole. It has not happened this year from a hole this deep.

The case for a quick recovery

There is a serious case that July was a jam that clears. Sea-Intelligence wrote on Aug. 19 that reliability “remains somewhat stable around 60‑65%”; if that band describes the norm, July's reading is the outlier, and February's dip lasted one month. And one recent source of pressure may prove temporary. Sea-Intelligence reported on Aug. 5 that major North American West Coast ports processed 3.7 million TEUs of laden imports, up 7.1% from a year earlier, with Los Angeles and Long Beach up 13.8% and 12.0%. The firm tied that second-quarter surge to tariff deadlines. If the surge was cargo shipped early to beat those deadlines, the pressure it added would fade once they passed.

Drewry reported on Aug. 26 that its Global Container Port Throughput Index rose 2.2% month on month in June and stood 1.2% higher than a year earlier. Ports were handling more boxes in June, not fewer. But that index counts boxes moved, not how much room terminals have, and June is the month before reliability fell. It cannot say whether the July jam came from heavier volumes or from terminals that could not keep up.

Carriers are thinning their schedules too. Drewry's cancelled sailings tracker counts 58 blank sailings, voyages cancelled in advance, expected between late September and the start of November, out of 712 planned, an 8% cancellation rate. Drewry said the cancellations are concentrated on the transpacific eastbound trade, which accounts for 64% of them, followed by Asia–North Europe/Med at 28%, with the rest on the Transatlantic. Fewer ships calling at crowded Asian ports would, in time, give the queues room to drain.

Both relief valves, though, work mostly on the months after August. The cancellations Drewry counts begin at the end of September. The tariff surge showed up in second-quarter imports, before July's collapse rather than after it. Neither speaks directly to the ships that sailed in August, and that timing is the weak point in the rebound case.

If August stays under the line, the cost lands unevenly. Sea-Intelligence ranked Wan Hai the least reliable carrier in June, and carriers already at the bottom of the table have the least cushion. Lines at the top, like Maersk and Hapag-Lloyd, would keep a punctuality edge that is easier to sell when the average is falling. Cargo owners carry the rest, in stock that arrives later than planned.

The two sides move at different speeds. Carriers can act within weeks, and most of the cancellations in Drewry's tracker fall on trades that begin in Asia, where the queues formed. Cargo owners have fewer quick levers: a shipper can rebook future cargo, but cannot make a ship already at sea arrive sooner.

Spot freight prices, the rates for shipping a container at short notice, slipped this week. Drewry reported on Sept. 24 that its World Container Index decreased 1% to $4,468 per 40ft container. That reading covers late September, not July, so it cannot show who bore July's delays; it shows only that spot prices were not climbing.

The test arrives within days. A Sea-Intelligence August figure at or above the threshold would mean reliability climbed back from July the way it did once earlier this year, this time from a deeper hole. A figure below the line would show July was not a one-month blip. Either way, one global average will not show which ports are still backed up.

In July, by Sea-Intelligence's count, no carrier improved and every one of the region's busiest ports lost on-time arrivals. The relief on offer, a Red Sea return about a quarter complete and sailing cancellations that begin in late September, looks too slow to lift August back over the line.