A passenger aircraft with 337 people on board was forced to divert in February after the pilot spilled coffee on the controls panel, UK investigators say.
The Airbus A330-243 from Frankfurt, Germany, to Cancun, Mexico, had to land in Shannon, Ireland, the Air Accidents Investigation Branch (AAIB) reports.
This was because the pilots' audio control panels (ACP) started melting and there was smoke in the cockpit.
The pilots had to used oxygen masks. There were no injuries.
The AAIB does not identify which company operated the flight during the accident on 6 February 2019.
However, the Flight Safety Foundation independent non-profit organisation says it was a Condor Airlines flight. The plane was operated by Thomas Cook Airlines.
What are the details of the cockpit accident?
The AAIB says the main pilot was monitoring the co-pilot over the Atlantic Ocean when coffee was served.
The drinks were given in cups without lids, which the AAIB says was normal for the company operating the flight.
The main pilot put the coffee on his tray table - but the cup was later knocked over.
Most of the liquid fell onto the commander's lap and a small amount spilled on the main ACP1.
The ACP1 and later the co-pilot's ACP2 soon became hot enough to start melting one of its buttons.
This resulted in the control panels failing, and communication difficulties.
The decision was taken to divert to Shannon, and the plane landed safely.
The AAIB says that the operator has since changed their procedure to ensure that cup lids are provided for flights on all routes, and cabin crews are reminded of the requirements to use them.