Carriers are increasingly reshaping published sailing schedules to absorb disruption across global liner networks, a shift that is now distorting how vessel delay performance is measured at a global level.
Issue 770 of the Sea-Intelligence Sunday Spotlight examines the growing use of structural schedule buffering by container shipping lines and the resulting distortion in global vessel delay metrics.
Sea-Intelligence assesses this trend through the Schedule Padding Index (SPI) alongside monthly early arrival counts. A negative SPI indicates greater schedule buffering and aligns with a higher proportion of vessels arriving ahead of schedule.
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During the 2012–2019 pre-pandemic period, the global SPI averaged +0.06 days, with early arrivals accounting for 1.9 per cent of global deep-sea traffic, or around 219 vessels per month.
This shifted significantly during the pandemic recovery phase in 2022, when the SPI dropped to -0.20 days and early arrivals rose to an average of 716 vessels per month, representing 6.9 per cent of global arrivals.
According to Sea-Intelligence, this reliance on structural buffering has remained evident into 2026. Year-to-date, the SPI has averaged -0.14 days, while early arrivals have stayed elevated at an average of 486 vessels per month.
The report links this sustained pattern to ongoing network disruption, including extended diversions via the Red Sea and Strait of Hormuz, as carriers adjust schedules to accommodate longer and less predictable voyage routes.
While schedule padding helps carriers present improved reliability metrics, it also distorts interpretation of global delay data by shifting a growing share of variability into early arrivals rather than late ones.
For more information:
Sea-Intelligence – https://www.sea-intelligence.com/
