Five leading indicators that predict shipping disruption before the news does

By the time a shipping disruption is a headline, the useful decisions have already been made by people who saw it first. None of them had inside information. They were watching indicators that move before the news does, all of which are publicly observable.

Here are five, roughly in order of how much warning they give.

1. War-risk insurance premiums

Warning: days to weeks.

Marine insurers price war risk for specific sea areas, and they reprice quickly because their exposure is immediate. A premium that doubles for a corridor is a group of professional risk assessors concluding that the probability of loss has changed materially.

Carriers watch the same number. A sustained premium increase is usually followed by routing changes, because at some point the insurance cost exceeds the cost of sailing further.

This is the single most reliable leading indicator available, and it is the one least used by supply-chain teams, mostly because it sits in an insurance publication rather than a logistics one.

2. Vessels going dark on AIS

Warning: hours to days.

The Automatic Identification System broadcasts vessel position continuously. Ships switch off the transponder, or broadcast implausible positions, when the crew judges that being visible is a risk.

A handful of gaps means nothing. A pattern of gaps in one area means masters are making the same judgement independently, which is worth more than any single announcement. It tells you the people physically present consider the area dangerous.

3. Booking and blank-sailing behaviour

Warning: one to three weeks.

Carriers cancel sailings — "blank sailings" — when they expect to reposition capacity. A cluster of cancellations on one lane means the carrier is already planning around a disruption they have not announced.

You can see this without any special access: compare the published schedule against the same schedule a fortnight earlier. Sailings that quietly disappeared are the signal.

4. Canal and port authority notices

Warning: weeks to months.

The most forecastable disruption on the map is the Panama Canal, because its constraint is water. The canal authority publishes daily transit slot allocations and draught restrictions in advance, and lake levels fall gradually and measurably.

Port authorities publish congestion statistics and berth availability on a similar basis. These are dull documents that almost nobody in a buying team reads, and they contain the clearest forward information available anywhere.

5. Charter and freight rate divergence

Warning: days to weeks.

When rates on one lane rise sharply while comparable lanes stay flat, the market is pricing something specific to that lane. Divergence matters more than absolute level: a general rise is a capacity story, but one lane moving alone is a routing story.

Charter rates for the vessel class serving that lane tell you the same thing one step earlier, because carriers secure tonnage before they publish rates.

Using them together

No single indicator is decisive. Insurance premiums rise for reasons that never materialise; AIS gaps happen for mundane reasons; blank sailings occur for commercial ones.

What makes them useful is agreement. When premiums rise and AIS gaps cluster and sailings start disappearing from the schedule, you are no longer guessing — and you still have days before the routing announcement that will make it everyone's problem at once.

That gap is the entire value. It is the difference between pre-booking an alternative at a normal rate and bidding for whatever is left.