Definition
ETA is when the ship expects to arrive — usually at the pilot boarding place or the anchorage, not the berth. ETB is when she expects to be alongside, which depends on the berth being free. ETD is when she expects to sail, set by the end of cargo work and of critical services: bunkers, provisions, waste removal and clearances. IMO's Just In Time Arrival Guide adds the "requested" and "actual" versions of each (RTA, ATA and so on) and notes that roughly 80% of ships calling at a container port must wait for another ship to leave the berth.[1]
The waiting is expensive: IMO reports ships spend up to 9% of their time waiting at anchorage, which is why the guide argues for arriving "just in time" at an optimal speed once berth, fairway and pilots are all available. The timestamps used in port notifications are defined under the IMO FAL Convention, whose Annex governs the formalities of a ship's arrival, stay and departure.[2,1,3]
For supply, ETB and ETD matter more than ETA: they decide whether goods go alongside by truck or out by launch, and the latest time an order can still be delivered. Give suppliers all three, and update them — a requisition quoted for a berth delivery is a different price at the anchorage.
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Sources
- [1] IMO / GloMEEP Low Carbon GIA — Just In Time Arrival Guide (PDF) — https://ghgsmart.imo.org/wp-content/uploads/2023/02/GIA-just-in-time-hires.pdf
- [2] IMO — Just In Time Arrival Guide published (11 Aug 2020) — https://imo.org/en/MediaCentre/Pages/WhatsNew-1502.aspx
- [3] IMO — Convention on Facilitation of International Maritime Traffic (FAL) — https://www.imo.org/en/OurWork/Facilitation/Pages/FALConvention-Default.aspx
A working definition for buyers, not legal advice — the contract, the convention text and your club or class have the last word.