A pilot involved in a fatal light aircraft crash was flying in conditions he was not qualified for, a year-long investigation has concluded.

Pilot Tony Woodward, 62, and his friend Bob Archer, 57, died when their plane crashed into the sea in thick fog near the Kintyre peninsula on May 25 last year.

The Air Accidents Investigation Branch (AAIB) found Mr Woodward had not completed the required training to fly in visibility below 1500 metres.

He had flown from Carlisle Lake District Airport to Oban on May 20 before completing an ascent of Ben Nevis for charity. It was during their return to Cumbria that the crash occurred.

Air traffic controllers raised the alarm after communication with the Piper PA-28 Cherokee aircraft ceased.

Floating wreckage and the bodies of the men were later recovered from the sea.

The AAIB reported Mr Woodward "might not have been aware of how poor the conditions had become" due to the gradual reduction in visibility.

"Flying in such conditions would have markedly increased the pilot's workload and stress while reducing his capacity to make decisions," the report concluded.