A light aircraft crash that killed a young couple may have been caused by the pilot becoming disoriented while flying the plane, investigators have suggested.

An Air Accident Investigation Branch (AAIB) report into the crash could not identify a specific cause for the accident but suggested the pilot, 28-year-old David Rous, may have become disoriented after losing visibility.

Mr Rous was flying the Piper Cherokee with his wife, GP Margaret Ann Rous, as a passenger when the plane took off from Dundee. The aircraft went down near Loch Etive in Argyll and Bute.

The couple, who lived in Newport in Fife, were reportedly heading from Dundee to visit relatives on the Hebridean isle of Tiree.

Published on Thursday, the AAIB report noted the plane began a right turn after receiving a weather report at 10.27am on April 4.

It said: "It is likely the pilot realised it was not going to be possible to continue the flight and decided to return to Dundee or another airfield."

The report said Mr Rous was a pilot of "above average standard" and was "responsible" when visibility was lost in a previous flight.

It added: "The recorded data indicates that the apparently level and controlled turn developed into a spiral dive, consistent with some form of spatial disorientation."

The pilot was likely to have been unable to see the horizon, it added.

Investigators also noted the plane was flying close to the freezing level and could possibly have experienced icing.

The report concluded: "No specific cause for the accident could be identified but the descent in IMC (instrument meteorological conditions) with extreme aircraft attitudes suggests the pilot was experiencing some form of spatial disorientation."

A major search was launched for the aircraft after it lost contact with air traffic control. Searchers later found the wreckage near a remote path.