Underwater operations 16 feb thru 23 mar by M/V thalassa in area bound by 00-00S 023-00W, 00-00S 000-00W,…
South Atlantic Ocean · HYDROLANT 520/20
What this record establishes
Archived notice · 2020-02-18 11:49Z
This notice comes from the historical archive. Its archived status does not establish when or how the reported situation ended.
- Source and dates
- NGA MSI broadcast-warn JSON (archive, frozen 2024-05) · NAVAREA VII 43/20 131121Z FEB 20.. Issued 2020-02-13 13:09Z. First collected 2026-08-17 13:38Z; last seen in collection 2026-08-17 15:46Z. Collection dates record ingestion, not a new incident or a fresh field observation.
- Location covered
- South Atlantic Ocean. The map shows an area described by the warning; the listed coordinate is its representative center. Check the original wording for limits and qualifications.
Related notices and cancellation links
- Underwater operations 16 feb thru 23 mar by M/V thalassa in area bound by 00-00S 010-00W, 00-00S 000-00W,…cancelled by this notice
- Cancel HYDROLANT 520/20(24,57)later cancellation notice
Current notices and reporting history in the South Atlantic Ocean →
- issued
- 2020-02-13 13:09Z
- status
- Archived notice
- authority
- NAVAREA VII 43/20 131121Z FEB 20.
- NAVAREA
- NAVAREA VII · named as the source of this relay
- sea
- South Atlantic Ocean
- position
- -5.792, -12.896
- vessel
- M/V THALASSA · 139 messages
- source
- NGA MSI broadcast-warn JSON (archive, frozen 2024-05) · first seen 2026-08-17 13:38Z
Original warning text
SOUTH ATLANTIC. DNC 01. 1. UNDERWATER OPERATIONS 16 FEB THRU 23 MAR BY M/V THALASSA IN AREA BOUND BY 00-00S 023-00W, 00-00S 000-00W, 06-00S 010-00W, 20-00S 010-00W. WIDE BERTH REQUESTED. 2. CANCEL HYDROLANT 510/20. 3. CANCEL THIS MSG 24 MAR 20.
Reading this warning
- DNC (Digital Nautical Chart)
- A reference to one of the regions of NGA's Digital Nautical Chart, used to tell the reader which charts a warning affects.
- Underwater operations
- Divers or remotely operated vehicles are working below a vessel that cannot easily move out of the way.
- Area bound by
- Introduces a list of positions that are the corners of an area — the polygon the warning applies to.
- Position (degrees and minutes)
- How warnings write positions: degrees, a hyphen, then minutes, with N/S and E/W — 49-40.8N 003-43.8W.
- Wide berth requested
- Keep well clear — or, when a distance is given ("TWO MILE BERTH REQUESTED"), at least that far away.
- Cancellation reference
- A line that cancels an earlier warning by its number, such as CANCEL HYDROLANT 1085/12.
- HYDROLANT
- The U.S. long-range warning series for Atlantic waters outside NAVAREA IV, including the eastern Atlantic, the Mediterranean and adjoining seas.
- CANCEL THIS MSG
- The warning's own expiry: a line telling the reader when the message cancels itself.
Collected reports in this area · survey operations
2 within 180 nm since 2020 · 0 in the last 12 months · 0 listed in force now
Counts include repeat notices about the same situation. NGA archive coverage ends 2024-05; live collection began 2026-08-17. The period between them is incomplete. An empty year is not evidence that no hazards occurred.
Month of issue in the collected archive
All available years combined. Uneven collection and repeat bulletins affect these counts; this chart does not measure the seasonality or probability of incidents.
Nearby notices listed in force · within 120 nm
No other collected notice is currently listed in force within this radius. This does not establish safe conditions.
Worldwide in the collected sources
56 survey operations listed in force · see all
Record snapshot 2026-10-03 01:19Z; source collection times vary.
Surveys
Hydrographic and scientific survey vessels, often towing long arrays. All current survey operations →
Not for navigation. This is a re-rendering of an official navigational warning for awareness; mariners must use official NAVAREA broadcasts and their national MSI service.