You check a container on Monday and the arrival date is the 14th. On Thursday it says the 16th. The next week it says the 15th. If you plan a truck, a warehouse slot or a sale around that date, every change costs you time.
Here is where that date comes from, why it moves, and what BerthTime adds next to it.
What the carrier's ETA is
ETA means "estimated time of arrival". For a container, it is the date the shipping line expects the vessel to arrive at the port of discharge, the port where your container comes off the ship.
The shipping line publishes this date from its schedule. It is the official date.
Why it keeps changing
A sea trip takes weeks. The shipping line updates its schedule as the trip goes on. Common reasons:
- A late departure. If the vessel leaves the first port late, everything after it moves too.
- Bad weather. Storms slow ships down.
- A busy port. Ships can wait at anchor before they get a place at the quay.
- A ship change. Many containers change ship on the way, at a transshipment port. If the next ship leaves later than planned, the container waits.
So a changing ETA is normal. The problem is that you often learn about the change late.
How BerthTime shows the carrier's ETA
BerthTime updates every shipment automatically in the background. You never need to press a button to get the latest news.
On each shipment you see:
- the latest ETA from the shipping line, with the number of days left;
- the original ETA, the first arrival date BerthTime saw;
- the delay compared with the original, for example +2d, or On schedule when the dates match.
A shipment whose arrival date is later than the first date BerthTime saw is marked Delayed. You can get an email when that happens: set an alert rule for a delay of a number of days or more, or for an ETA that moves later in one change. See how to track a container to get started.
What a predicted ETA adds
The carrier's ETA only moves when the shipping line updates it. A vessel can be running late for days before that happens.
So when a ship is at sea, BerthTime makes its own estimate. It looks at:
- where the vessel is now, from the position signals ships send (AIS);
- how far it still has to go, along the usual sea routes to its next ports;
- how fast it has been sailing recently;
- any ship change still ahead, with time to wait at that port.
The result is the Predicted arrival. It is always labelled "Estimate based on vessel position", so you never mix it up with the carrier's date. The carrier's ETA stays the reference.
Each estimate also has a confidence: low, medium or high. It is higher when the vessel's position is recent, when no ship change is left and when the arrival is close. Far out at sea, ships can be out of reach of the receivers on shore for a while. The estimate then uses the last known position and its confidence goes down.
There is no prediction when no vessel is known yet, when the container is not at sea (before departure, or while it waits at a transshipment port), or after arrival. You then see the carrier's ETA only.
The risk badge, in plain words
BerthTime compares its estimate with the carrier's ETA and shows a small badge on the shipment and in your shipment list:
- On time: our estimate is not more than about half a day after the carrier's date, or it is earlier.
- At risk: our estimate is between about half a day and one day later. It also says At risk when the gap is bigger but the confidence is low.
- Likely late: our estimate is more than one day after the carrier's date, and the confidence is medium or high.
"Likely late" does not mean the carrier is wrong. It means the vessel's position and speed point to a later arrival than the published date.
You can filter your shipment list to see only the shipments that are likely late. You can also get an email when a shipment is predicted to arrive a number of days after the carrier's date. That alert is only sent when the confidence is medium or high, so a rough guess does not fill your inbox.
What to do with it
Use the carrier's ETA for your paperwork. Use the predicted arrival and the risk badge as an early warning: to call your trucker, move a warehouse slot or tell your customer before they ask.
You can also ask your AI assistant. "Which of my shipments are likely to arrive late?" works in ChatGPT and Claude once you connect BerthTime.
Start a free trial and add a few containers to see both dates side by side.