Nav aids

GPS jamming exercises 1300Z to 1500Z daily 25 thru 27 may in area within 32 miles of 52-08.5N 004-34.3W…

Irish Sea and St. George's Channel · HYDROLANT 1399/21

What this record establishes

Archived notice · 2021-05-27 16:00Z

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) · WZ 568/21 250318Z MAY 21.. Issued 2021-05-25 06:52Z. 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: Irish Sea and St. George's Channel. The parsed report position is 52.142, -4.572 with a 32.0 nm radius. It is a position in the source message, not a live location. Check the original wording for limits and qualifications.

Current notices and reporting history in the Irish Sea and St. George's Channel →

Activity windows · 3 in this warning

opens (UTC)	closes (UTC)	local	length
2021-05-25 13:00Z	2021-05-25 15:00Z	—	2 h
2021-05-26 13:00Z	2021-05-26 15:00Z	—	2 h
2021-05-27 13:00Z	2021-05-27 15:00Z	—	2 h

Parsed from the warning text; outside these windows the area is normally not active, but the warning stays in force until cancelled.

issued: 2021-05-25 06:52Z
status: Archived notice
self-cancels: 2021-05-27 16:00Z
authority: WZ 568/21 250318Z MAY 21.
issued by: WZ
sea: Irish Sea and St. George's Channel
position: 52.142, -4.572 · r 32.0 nm
source: NGA MSI broadcast-warn JSON (archive, frozen 2024-05) · first seen 2026-08-17 13:38Z

Original warning text

CARDIGAN BAY.
WALES.
DNC 20.
1. GPS JAMMING EXERCISES 1300Z TO 1500Z DAILY
   25 THRU 27 MAY
   IN AREA WITHIN 32 MILES OF 52-08.5N 004-34.3W
   BETWEEN 340 DEGREES AND 025 DEGREES.
2. CANCEL THIS MSG 271600Z MAY 21.

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.
GNSS / GPS: Satellite positioning — GPS and other systems — and the testing, jamming and interference that make it unreliable in an area.
Within a radius of: A circular area — every position within a stated distance of a point.
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.
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.

All warning terms →

Collected reports in this area · aids-to-navigation notices

1796 within 180 nm since 1997 · 3 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

134 aids-to-navigation notices listed in force · see all

Record snapshot 2026-10-02 21:40Z; source collection times vary.

Nav aids

Lights extinguished, buoys off station, RACON/NAVTEX outages. All current aids-to-navigation notices →

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.