A Cumbrian entrepreneur who was killed in his helicopter last year was 'not qualified to fly at night', a report has found.
Mark Weir, 45, from Cockermouth, died on 8 March 2011 after his helicopter crashed shortly after taking off from the Honister Slate Mine that he owned in the Lake District.
A report by the Air Accident Investigations Branch has found that Mr Weir did not hold a night-flying qualification and had taken off in 'challenging circumstances' with reduced visibility and low cloud.
The report said:
" A number of serious airworthiness issues were identified with the helicopter during the course of the investigation. None of these could be directly linked to the cause of the accident but did raise concerns regarding the way the helicopter was operated."
Mr Weir flew regularly between his home and the mine, which attracted 60,000 visitors a year.
The report also said there was no evidence of mechanical failure and that it was "not possible to determine the mechanism by which control was lost or disorientation occurred".