Exercises

Hazardous operations 250830Z to 251759Z apr, alternate 260830Z to 261759Z apr in areas bound by: a. 13-45N…

North Pacific Ocean · HYDROPAC 1539/18

What this record establishes

Archived notice · 2018-04-25 13:09Z

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) · WESTERN RANGE 092237Z APR 18.. Issued 2018-04-20 08:42Z. 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
North Pacific 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

Current notices and reporting history in the North Pacific Ocean →

Activity windows · 2 in this warning

opens (UTC)closes (UTC)locallength
2018-04-25 08:30Z2018-04-25 17:59Z—9 h 29
2018-04-26 08:30Z2018-04-26 17:59Z—9 h 29

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

issued
2018-04-20 08:42Z
status
Archived notice
self-cancels
2018-04-26 18:59Z
authority
WESTERN RANGE 092237Z APR 18.
issued by
WESTERN RANGE
sea
North Pacific Ocean
position
12.956, 174.065
source
NGA MSI broadcast-warn JSON (archive, frozen 2024-05) · first seen 2026-08-17 13:38Z

Original warning text

NORTH PACIFIC.
DNC 12.
1. HAZARDOUS OPERATIONS 250830Z TO 251759Z APR,
   ALTERNATE 260830Z TO 261759Z APR
   IN AREAS BOUND BY:
   A. 13-45N 173-28E, 14-24N 175-53E,
      12-59N 176-17E, 12-20N 173-52E.
   B. 12-35N 171-10E, 12-52N 171-42E,
      12-03N 172-22E, 11-10N 172-45E,
      10-55N 172-13E, 11-45N 171-34E.
2. CANCEL THIS MSG 261859Z APR 18.

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.
Hazardous operations
NGA's heading for activities that make an area dangerous — most often rocket launches, space debris and weapons firings, and some open-ended danger areas.
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.
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.
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 · military exercises

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

99
00
05
10
15
20
23

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

10 military exercises listed in force · see all

Record snapshot 2026-10-03 06:32Z; source collection times vary.

Exercises

Gunnery, firing and naval exercise areas. All current military exercises →

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.