JUNE 2026 | AIS INTELLIGENCE BLOG
When a commercial fishing vessel runs aground in the Inside Passage, the first call after the Coast Guard is to the underwriter. The second call, increasingly, is to whoever has the AIS data.
This post walks through how a maritime insurance investigator would use AIS archive data to reconstruct a grounding event — from the vessel's last known good position, through the dark period, to the first responder arrival.
AIS transmitters broadcast position every 2-10 seconds for Class A vessels and every 3-180 seconds for Class B. An AIS receiver network with good coverage — shore stations plus satellite — captures 95%+ of commercial traffic. That record is a timestamped track of exactly where a vessel was and how fast it was going.
In an incident investigation, this answers:
Here's a typical workflow using AIS archive data.
You need the MMSI of the vessel, which is on the documentation and in any USCG report. With the MMSI, you query the archive for the 24 hours before the incident:
GET /v1/export?mmsi=338234631&start=2026-05-14T00:00:00&end=2026-05-15T06:00:00&format=csv X-API-Key: your-key
This returns a CSV with one row per position fix: timestamp, lat, lng, SOG, COG, heading.
Plot the track. Look for the point where SOG drops sharply to zero and the signal goes dark. That's your grounding candidate. Compare it against chart datum — NOAA Electronic Navigational Charts are freely available as GeoJSON and can be overlaid against the AIS track.
Use the gap analysis endpoint to flag any AIS dark periods:
GET /v1/intelligence/gaps?mmsi=338234631&days=2&min_gap_hours=0.1 X-API-Key: your-key
A gap of more than 30 minutes in a coastal area with good AIS coverage is suspicious. A gap that starts exactly at a charted shoal is often conclusive.
Query the area around the grounding site for other vessels in the same window. This rules out collision scenarios and establishes whether anyone witnessed the grounding:
GET /v1/vessels/live?bbox=56.1,-134.8,57.2,-133.5&minutes=120 X-API-Key: your-key
The CSV export from Step 1, combined with the gap analysis from Step 3, is typically enough to support an insurance claim assessment or USCG incident report. The data is timestamped, position-verified, and produces a clean narrative: the vessel departed X at T1, maintained Y knots on course Z, and went dark at position P at T2.
AIS data establishes track and timing. It cannot prove operator intent, mechanical failure, or cause. It is evidence of where a vessel was, not why it went there. In combination with voyage data recorder downloads, weather records, and witness statements, it is one of the strongest objective datasets available to investigators.
AIS Intelligence provides a 400-day archive for Alaska, Hawaii, and the Pacific Northwest at $199/mo after a free 7-day trial. The historical export endpoint returns CSV or JSON and integrates directly into Excel, QGIS, or Python analysis pipelines.