Aviation investigators in the U.K. have cited mechanical failure as the cause of a terrifying mid-air drama involving British royal Charles, Prince Of Wales last year (13).

The heir to the British throne was travelling with his wife, Camilla, Duchess of Cornwall, in a helicopter last May (13) when the aircraft veered out of control, prompting the pilots to make an emergency landing.

No one was hurt in the incident, but the royals were left shaken.

An investigation was launched into the cause of the near-miss and officials at the U.K.'s Air Accidents Investigation Branch (Aaib) have now released their findings, citing a mechanical fault for causing the drama.

The report reveals part of the helicopter's control system broke, leaving the pilots unable to fly the aircraft in a straight line.