Liner reliability turns extreme: weak Januaries, sharp summer peaks

MSC posted schedule reliability of 68.9% across the east-west container trades in August and September, narrowly ahead of rivals, while Maersk held its position as the most reliable carrier overall — though the Gemini alliance its network anchors showed hits and misses across the trades, according to Sea-Intelligence's Global Liner Performance review.

The monthly punctuality numbers sit on top of a structural shift the Copenhagen consultant says has hardened since the pandemic: global schedule reliability has become markedly more seasonal, and weekly service deployments on the main east-west lanes have grown far more volatile.

What does the data actually show?

Sea-Intelligence drew on its Global Liner Performance database, which tracks monthly vessel arrivals from July 2011 to September 2026. Two findings stand out.

First, the relationship between punctuality and delay severity has tightened. Historically, falling reliability went hand in hand with longer delays. Since the pandemic, that correlation has settled at a lower sustained level — meaning there is now a tighter link between whether a vessel arrives late at all and how late it actually is than was evident before 2020. Late arrivals are fewer but more predictable in magnitude, on the consultant's reading of the data.

Second, the seasonal shape of global reliability has changed. Between 2013 and 2019, the pre-pandemic norm was clear: reliability fell in the early months of the year, improved through spring and early summer, dipped slightly in late summer, then reached a second peak in October and November. Since 2020, individual years have drifted away from that template. Comparing average monthly reliability across the two periods, Sea-Intelligence found seasonal swings have become more pronounced — weaker starts to the year, higher performance peaks in summer. The overall pattern, the consultant said, has become more extreme.

How volatile have east-west deployments become?

A separate analysis, using Sea-Intelligence's Trade Capacity Outlook database, counted weekly services on four major routes: Asia–North America West Coast, Asia–North America East Coast, Asia–North Europe and Asia–Mediterranean.

The methodology strips out noise from new launches and cancellations, blank sailings, schedule slippage and seasonal or niche services, then measures consistency as the annual standard deviation in weekly service numbers as a percentage of the average services operated.

The result: a clear upward shift from 2020 on all four trades. Comparing average variability in 2013–2019 with 2020–2026:

• Asia–North America East Coast: smallest increase, at 26%
• Asia–North Europe: largest increase, at 78%
• Asia–Europe routes generally saw variability rise more sharply than the transpacific

That spread matters for shippers. An NAC shipper booking east coast loops faces a modestly less predictable weekly product; a North Europe importer faces a service schedule that has become dramatically less stable week to week, complicating everything from warehouse slotting to inland transport planning.

Why should terminals and forwarders care?

The implications run beyond cargo owners and logistics providers wrestling with planning. Greater week-to-week fluctuation in service numbers makes it harder for container terminals to plan resources and manage workloads, because the number of vessels and the volume of cargo requiring handling can swing sharply from one week to the next.

Sea-Intelligence warned this raises the risk of sudden congestion — which can, in turn, undermine schedule reliability further. Volatility feeds back on itself: erratic deployments strain berth and yard capacity, congestion delays vessels, and delays erode the very reliability carriers are trying to rebuild.

For carriers, the data poses a harder question. Alliance structures such as Gemini were sold on schedule discipline, and Maersk's spot as the most reliable carrier suggests hub-and-spoke control still delivers. But the aggregate numbers show the industry product remains hostage to seasonal extremes and deployment whiplasm seven years after Covid first broke the old rhythm.

With reliability now weakest in the early months of the year and most volatile on Asia–Europe, shippers and forwarders should expect the tightest capacity planning windows around Chinese New Year and the strongest service consistency — by the new seasonal pattern — in mid-summer, unless carriers move to damp the deployment swings.