Boat owners in Scottish waters have been warned that GPS signals may be periodically jammed by the Ministry of Defence next month.

The jamming is part of Exercise Joint Warrior, which will take place between 16-26 April, and may also disrupt mobile phone signals.

A sécurité message will be broadcast by Stornoway and
Shetland Coastguard prior to and on completion of the jamming period, during
which time GPS receivers and any related equipment may suffer
intermittent/total failure, or give incorrect position info or default to DR

If this occurs, DCS is to be manually updated at regular intervals, but
boaters should be aware of these limitations and use alternative means of
navigation during jamming periods to confirm their position and check the
equipment on completion.

The area affected lies within the North Minch
northwards from Rubha Réidh 57-52N 005-48W to Stoer Head 58-14N 005-24W and within 35 nautical miles line of sight from the Faraid Head jamming site,
depending on receiver antenna height.

“Denial of GPS services through the
jamming of the GPS signal is an essential part of preparation for military operations”, said the Joint
Tactical Exercise Planning Staff, “and is a possible risk to both military and civilian maritime and air users.”