SriLankan Airlines' safety rating has been downgraded from seven to six stars by AirlineRatings.com following a reported incident involving a captain locking his female co-pilot out of the cockpit during a 10-hour flight from Sydney to Colombo.

The caption involved in the incident has resigned as well.

The incident occurred on a SriLankan Airlines Airbus A330-300, flight UL-607, with the aircraft registered as 4R-ALR. According to the Aviation Herald, the event unfolded while the plane was en route to Colombo. The co-pilot had stepped out of the cockpit for a restroom break when the captain locked the door, preventing her from re-entering. Despite the situation, the aircraft landed safely in Colombo.

The co-pilot lodged a formal complaint after landing, citing a disagreement with the captain as the cause of the lockout. Reports from other media sources indicate that the situation escalated to the point where a senior cabin crew member had to intervene, using the intercom system to persuade the captain to unlock the cockpit door and allow the co-pilot back to her seat.

SriLankan Airlines has since grounded the captain, and the Civil Aviation Authority of Sri Lanka has launched an investigation into the matter.

AirlineRatings.com described the incident as extremely serious, leading to the airline's safety rating downgrade.