Calculated ETAs, Vessel Events and Weekly Port Congestion Medians
Calculated fields sit beside raw AIS fields, and they are not the same thing. ETA is whatever the crew typed; ETA_CALC is what MarineTraffic worked out, with ETA_UPDATED recording when it did the sum and SPEED_CALC the speed it used. Destination is free text of up to 20 characters; the resolved next port id, UN/LOCODE and name are the platform's reading of it, and they come back empty when the string is an abbreviation nobody recognises, when the crew never updated it, or when the last position is hours old. Carrying both columns is the only way to audit that gap later.
Events are a separate stream with their own ids. First and intermediate daily position for the midnight and noon reports, in range and out of range, stopped and underway, drifting, AIS off when a transponder goes quiet inside covered water, name changed, flag changed, destination changed, and the proximity events that mark ship-to-ship work. Those are the rows a due diligence or sanctions workflow keys on, next to the platform's spoofing notes on position jumps and duplicate identities.
Congestion is computed weekly, not watched live. It arrives as median days at anchorage and median days in port, per port, per week, per market and per size class, with week-on-week differences and the vessel and call counts behind each median. Markets are the platform's own taxonomy - container ships, dry bulk, dry breakbulk, wet bulk, LNG and LPG carriers, ro-ro, passenger, offshore and rigs, fishing and pleasure craft - and size classes run small feeder to ULCV on TEU, handysize to VLCC on deadweight.