Nav aids

GPS jamming exercises 0730Z to 1500Z daily 24 thru 28 may in area within 20 miles of 54-50.3N 004-55.8W

Irish Sea and St. George's Channel · HYDROLANT 1384/21

What this record establishes

Archived notice · 2021-05-28 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 561/21 240109Z MAY 21.. Issued 2021-05-24 01:11Z. 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 54.838, -4.930 with a 20.0 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 · 5 in this warning

opens (UTC)closes (UTC)locallength
2021-05-24 07:30Z2021-05-24 15:00Z—7 h 30
2021-05-25 07:30Z2021-05-25 15:00Z—7 h 30
2021-05-26 07:30Z2021-05-26 15:00Z—7 h 30
2021-05-27 07:30Z2021-05-27 15:00Z—7 h 30
2021-05-28 07:30Z2021-05-28 15:00Z—7 h 30

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

issued
2021-05-24 01:11Z
status
Archived notice
self-cancels
2021-05-28 16:00Z
authority
WZ 561/21 240109Z MAY 21.
issued by
WZ
sea
Irish Sea and St. George's Channel
position
54.838, -4.930 · r 20.0 nm
source
NGA MSI broadcast-warn JSON (archive, frozen 2024-05) · first seen 2026-08-17 13:38Z

Original warning text

IRISH SEA.
SCOTLAND.
DNC 20.
1. GPS JAMMING EXERCISES 0730Z TO 1500Z DAILY
   24 THRU 28 MAY IN AREA WITHIN 20 MILES OF
   54-50.3N 004-55.8W.
2. CANCEL THIS MSG 281600Z 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

1980 within 180 nm since 1998 · 9 in the last 12 months · 0 listed in force now

98
00
05
10
15
20
25
26

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

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

Record snapshot 2026-09-29 13:48Z; 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.