The light has gone out on the world-famous Bell Rock beacon off the Angus coast.
Northern Lighthouse Board chiefs say a fault has plunged the 211-year-old structure into darkness.
And they are waiting for the right conditions to land a helicopter there to make the repair.
The Bell Rock is the world’s oldest operational sea-washed lighthouse.
It sits 11 miles off Arbroath and is clearly visible from the Angus town.
Residents noticed the light was not operating in recent days.
Ships have been warned about the fault.
Notice to Mariners in place
An NLB spokesperson said: “The Northern Lighthouse Board can confirm that the Bell Rock Lighthouse is currently not operating due to a defect.
“Mariners have been informed through an official Notice to Mariners which is issued through the Maritime and Coastguard Agency.
“Because the Bell Rock can only be accessed via a helicopter landing on a concrete platform at the base of the tower this requires a combination of low-tide, daylight and benign weather conditions.
“The first tide and daylight opportunity to access the lighthouse since the breakdown was today, Friday November 19.
“However poor weather prevented this,” said the spokesperson.
“NLB’s operations team are keeping the situation under constant review and will access the lighthouse as soon as it is safe to do so.”
The nature of the problem has not been revealed.
Miracle of engineering
Robert Stevenson built what is renowned as one of the wonders of the industrial world to protect ships from the infamous Inchcape reef.
The remarkable feat was completed between 1807 and 1810.
It stands 115 feet tall and its light is visible from 35 miles.
Keepers manned the Bell Rock until the 1980s when it was fully automated.
A recent Channel 5 documentary charted the lighthouse’s fascinating history.