A holiday flight operated by Thomas Cook-owned Condor, was forced to divert because the pilot spilled coffee over the cockpit controls.
The Airbus A330, carrying 337 passengers and crew, which was en-route from Frankfurt to Cancun, had to make an emergency landing in Shannon in the west of Ireland.
The UK-based Air Accident Investigation Branch said the spilt coffee caused the audio control panel to start melting and there was smoke in the cockpit, forcing the pilots to use oxygen masks.
No-one was injured in the incident on February 6 although five people were taken to University Hospital Limerick for treatment. It is understood they included four cabin crew members and a passenger who were reported to be suffering from smoke inhalation.
Passengers were forced to spend the night in Ireland due to the diversion, which is estimated to have cost the airline up to £80,000.
The report found the 49-year-old captain had put his coffee cup on a tray table – where objects are ‘vulnerable to being knocked over’ – despite Airbus recommending pilots use the cup holders provided.
The AAIB said the small size of cups used by Condor ‘generally discouraged’ use of the holders as it was difficult to grasp them.
Investigators also noted putting a lid on the cup may have reduced the amount of coffee spilled.
Condor responded to the accident by ensuring cup lids are provided on all flights, reminding pilots to be careful with liquids and supplying cups that are an appropriate size for cup holders.
