GNSS / GPS
Also written: GPS jamming, spoofing
Satellite positioning — GPS and other systems — and the testing, jamming and interference that make it unreliable in an area.
Two kinds of warning mention GPS. Planned tests: some governments announce periods when GPS signals may be unreliable in an area because of testing. Interference: since the early 2020s, jamming and spoofing have been reported widely in the eastern Mediterranean, the Black Sea, the Baltic, the Persian Gulf and the Red Sea, sometimes placing ships' positions kilometres inland.
Warnings about differential GPS (DGPS) stations going off air are notices about a correction service, not about the satellites.
What the archive shows
4,617 messages in this archive use “GNSS / GPS”, the earliest issued 1997-10-22 and the latest 2026-09-09. 1 of them is in force in the latest lists we collected. A hazard reported again and again counts once per message.
The largest yearly count is 2011, with 469 messages. Collection is incomplete between 2024-05 and 2026-08-17, so 2024, 2025 and 2026 are not comparable with fully collected years.
Nav aids accounts for 4,458 of 4,617 recorded messages (97%), the largest warning type group in this selection.
Located messages that use it fall in 37 sea areas; the most frequent are Gulf of Mexico (353), Coral Sea (340) and North Atlantic Ocean (320).
Its use is spread fairly evenly through the year: the busiest month, September, has 446 messages and the quietest, December, 316.
By warning series: HYDROPAC 1,356, HYDROLANT 1,190, NAVAREA XII 1,001 and NAVAREA IV 869, and 3 more.
Messages using it, by year of issue
By month of issue, all years
Where it appears · 37 sea areas
In force now · 1
- HYDROPAC 627/26 · Nav aids · Gulf of Oman2026-03-03 · in force
ARABIAN SEA. GULF OF OMAN. STRAIT OF HORMUZ. U.A.E. DNC 10. GPS, GNSS, AND AIS INTERFERENCE REPORTED IN VICINITY OF FUJAIRAH (25-07.33N 056-20.05E).…
GPS, GNSS, and AIS interference reported in vicinity of fujairah (25-07.33N 056-20.05E) →
How it reads in recent messages
- HYDROARC 222/26 · Nav aids · Norwegian Sea2026-09-08
NORWEGIAN SEA. NORWAY. 1. GPS JAMMING EXERCISES 0600Z TO 1600Z DAILY 09 THRU 18 AND 1600Z TO 2000Z DAILY 15 AND 16 SEP…
GPS jamming exercises 0600Z to 1600Z daily 09 thru 18 and 1600Z to 2000Z daily 15 and 16 sep in area bound… → - NAVAREA 19 111/26 · Nav aids · Norwegian Sea2026-09-08
NORWEGIAN SEA 1.GPS/GNSS JAMMING EXERCISE FROM 09 TO 18 SEPT 26. DAILY 0600-1600 UTC. 15 AND 16 SEPT…
Norwegian sea 1.GPS/GNSS jamming exercise from 09 to 18 sept 26 → - HYDROPAC 2632/25 · Nav aids2025-10-13
PERSIAN GULF. RED SEA. STRAIT OF HORMUZ. GPS, GNSS AND AIS INTERFERENCE REPORTED IN VICINITY OF NORTH AND CENTRAL PERSIAN GULF,…
GPS, GNSS and AIS interference reported in vicinity of north and central persian gulf, strait of hormuz and… → - NAVAREA XII 826/24 · Surveys2024-10-15
…THAT USE THE GEOMAGNETIC FIELD, INCLUDING ALL AIRCRAFT, SHIPS, SUBMARINES, AND GPS UNITS. 4. CANCEL THIS MSG 010001Z JAN 25.
World magenetic model (wmm) 2025 update 1. as part of the regular update cycle of the world magnetic model… → - HYDROPAC 3262/24 · Surveys2024-10-15
…THAT USE THE GEOMAGNETIC FIELD, INCLUDING ALL AIRCRAFT, SHIPS, SUBMARINES, AND GPS UNITS. 4. FOR SOME USERS THAT HAVE REQUESTED A WMM WITH PERFORMANCE THAT EXCEEDS…
World magenetic model (wmm) 2025 update 1. as part of the regular update cycle of the world magnetic model… → - HYDROLANT 2020/24 · Nav aids · Irish Sea and St. George's Channel2024-09-18
IRISH SEA. NORTH CHANNEL. ENGLAND. DNC 20. 1. GPS JAMMING EXERCISES 0730Z TO 1630Z DAILY 23 SEP THRU 04 OCT IN AREA WITHIN 22 MILES OF…
GPS jamming exercises 0730Z to 1630Z daily 23 sep thru 04 oct in area within 22 miles of 54-50.00N 004-56.00W → - HYDROLANT 1977/24 · Other · North Atlantic Ocean2024-09-11
SEA OF THE HEBRIDES. SCOTLAND. DNC 19. 1. RADAR JAMMING EXERCISES 0800Z TO 1700Z DAILY 16 SEP THRU 11 OCT IN AREA WITHIN 25 MILES OF 57-21.00N…
Radar jamming exercises 0800Z to 1700Z daily 16 sep thru 11 oct in area within 25 miles of 57-21.00N… →
Earliest in the archive
- HYDROLANT 1612/97 · Nav aids · English Channel1997-10-22
CHART 36180 (23RD ED). 1. RADIOBEACON AT LIZARD LIGHT 49-58N 005-12W OFF AIR AND DGPS SERVICE UNAVAILABLE 220700Z TO 221700Z OCT. 2. CANCEL THIS MSG 221800Z OCT.
Radiobeacon at lizard light 49-58N 005-12W off air and dgps service unavailable 220700Z to 221700Z oct →
Often in the same message
Related terms
- AIS (Automatic Identification System)
- The radio transponder system that broadcasts a ship's identity, position, course and speed — and can mark a hazard with a virtual beacon.
- Inoperative / unreliable / off air
- An aid or radio service is not working as charted or published.
- Piracy and armed robbery
- Attacks and attempted boardings of ships, and suspicious approaches by small craft.
Warning types that use it
Counts cover the messages in this archive that use the term, recounted 2026-09-24; see coverage for what is collected and since when. Not for navigation — follow official NAVAREA and coastal broadcasts.