The Duke of Edinburgh remains in hospital for a fourth day as he continues his treatment for a bladder infection.
Philip, 91, was rushed to Aberdeen Royal Infirmary on Wednesday while staying with the Queen during their annual summer break at Balmoral.
An RAF search and rescue helicopter was immediately dispatched to fly him to the hospital but poor visibility and heavy rain meant the crew, who are used to working in difficult conditions, were unable to reach him.
The Duke made the journey of almost 50 miles from the castle in the Cairngorms to the city hospital by road in an ambulance instead.
Doctors advised the Duke to rest on Friday, meaning there were no visits from other members of the Royal Family. But Philip is said to have been in constant contact with his relatives by phone.
He is expected to remain in hospital for the next few days and is said to be responding well to treatment for the recurrence of the infection he suffered in the summer.
The Sea King landed four times during the expedition on Wednesday, but could not get close enough. "The weather was absolutely dreadful," a source said.
At the hospital, a police presence could be seen outside, with four officers standing guard.
The Duke's latest health scare came two and a half months after he spent five nights in hospital with a bladder infection following the Diamond Jubilee Pageant on the River Thames. He was forced to miss some of the key celebrations for the Queen's 60 years on the throne after he was admitted to the King Edward VII Hospital in central London the day after braving wet and windy elements on a barge for several hours.
Philip also underwent a successful procedure to clear a blocked coronary artery last December and was in hospital for four nights over Christmas. Before the heart scare he had been fit and apparently healthy, and led the active life of a man of fewer years.