Surveys

Survey operations in progress until 111700Z apr by M/V tethys II in vicinity of trackline joining 41-22.0N…

Mediterranean Sea - Western Basin · HYDROLANT 762/23

What this record establishes

Archived notice · 2023-04-11 19:00Z

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 III 33/23 091202Z APR 23.. Issued 2023-04-09 16:51Z. 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
Mediterranean Sea - Western Basin. The map shows the reported line or operation extent; it is not a vessel track. Check the original wording for limits and qualifications.

Related notices and cancellation links

Current notices and reporting history in the Mediterranean Sea - Western Basin →

issued
2023-04-09 16:51Z
status
Archived notice
self-cancels
2023-04-11 19:00Z
authority
NAVAREA III 33/23 091202Z APR 23.
NAVAREA
NAVAREA III · named as the source of this relay
sea
Mediterranean Sea - Western Basin
position
41.117, 4.608
vessel
M/V TETHYS II · 36 messages
source
NGA MSI broadcast-warn JSON (archive, frozen 2024-05) · first seen 2026-08-17 13:38Z

Original warning text

WESTERN MEDITERRANEAN SEA.
BALEARIC ISLANDS.
DNC 08.
1. SURVEY OPERATIONS IN PROGRESS UNTIL 111700Z APR
   BY M/V TETHYS II IN VICINITY OF TRACKLINE JOINING
   41-22.0N 004-05.00E, 40-52.0N 005-08.0E.
2. CANCEL HYDRLANT 758/23.
3. CANCEL THIS MSG 111900Z APR 23.

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.
Survey operations
A research or survey vessel is mapping the seabed or water column, often while towing equipment.
Date-time group (DTG)
A compact UTC timestamp — day, hour and minute followed by Z — such as 201500Z for the 20th at 15:00 UTC.
Track line joining
Introduces a route through a series of positions — a cable route, a tow's track or a survey line.
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.
CANCEL THIS MSG
The warning's own expiry: a line telling the reader when the message cancels itself.

All warning terms →

Collected reports in this area · survey operations

84 within 180 nm since 1999 · 0 in the last 12 months · 0 listed in force now

99
00
05
10
15
20
24

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

J
F
M
A
M
J
J
A
S
O
N
D

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

55 survey operations listed in force · see all

Record snapshot 2026-10-01 08:32Z; 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.