The signal is occasionally taken off-air to allow maintenance work on the masts and antennas at Anthorn Radio Station to be carried out in safety. A radio-controlled clock will not be able to pick up the MSF signal during these periods, so may drift off from the correct time.
The shutdowns will take place between 10:00 and 14:00 BST in June and September, and between 10:00 and 14:00 UTC in December. The duration of each outage period will be kept to a minimum, and the signal may be back on-air prior to the times given above.
In addition to these dates, the signal is likely to be taken off-air for a two-week period during summer each year, though the transmission will be restored overnight whenever possible. The dates of this longer outage will be announced on this page and by emailed notices to registered users as soon as they are known.