When a vessel stops broadcasting AIS, that silence is itself a signal. Here's how to detect it.
A “dark ship” is a vessel that has stopped transmitting AIS when you'd expect it to be broadcasting. Sometimes it's innocent — an antenna fault, a power loss, a sat-gap. Sometimes it's deliberate, to mask a transfer, an incursion, or illegal fishing.
Our gap analysis endpoint walks a vessel's track and flags any silent interval longer than a configurable threshold, accounting for the looser reporting cadence of Class B units. The result is a list of dark periods with start, end, duration, and last-known position.
Legitimate reception gaps are common in the Aleutians and the deep fjords of Southeast Alaska. Naive dark-ship detectors light up with false positives here. Tuning thresholds to regional reception reality is the entire game — and the reason general-purpose global feeds perform poorly above 50°N.
Compliance teams export dark periods straight to CSV for incident files. Start a free trial and run gap analysis on any MMSI.