Every delay email starts the same way: "the ETA has changed." The problem isn't that ETAs change — voyages are physical processes and things happen. The problem is when you find out. A predictive ETA is an arrival estimate computed continuously from live data, rather than the static date printed on the booking — and the gap between the two is where planning goes wrong.
Static vs. predictive ETAs
The schedule ETA comes from the carrier's published rotation — set when you book, updated only when the carrier gets around to it, and famously slow to admit slippage. A predictive ETA starts from the same schedule but corrects it against live signals: where the vessel actually is right now, how fast it's going, what the queue looks like at the next port. When a ship departs Singapore nine hours late, a predictive ETA reflects that within minutes; the schedule ETA might catch up next week.
What feeds a predictive ETA
- Live AIS position & speed — the single most valuable input: actual progress versus plan, updated continuously at sea.
- Sailing schedules & rotations — the intended port sequence and connection times, essential for multi-leg (transshipment) journeys.
- Port congestion & dwell — how long ships are currently waiting at anchor and how long boxes dwell at that hub.
- Historical lane performance — what this service actually does on this lane, versus what the schedule claims.
What accuracy to expect
Honest numbers: mid-voyage ocean ETAs from live AIS are typically good to within about a day; they tighten to hours as arrival approaches. The volatile part isn't the sailing — it's transshipment: whether a box makes its connection at a hub can swing the final ETA by a week, which is why multi-leg shipments deserve the closest watching (see exception management). Air freight ETAs are inherently tighter (hours), and parcel ETAs are largely carrier-declared.
Using ETAs operationally
An ETA is only useful if something is scheduled against it: trucking booked against the live date, customs pre-filed ahead of arrival (see the demurrage guide for why), customers notified when the delivery week moves. That requires the ETA to live in a shared dashboard with alerts — not in a carrier portal nobody checks. That's the job Shyppy does: live positions, continuously updated ETAs and automatic alerts across ocean, air and courier, in one place.