A long haul passenger aircraft with 337 people on board was forced to divert after the pilot spilled coffee on the cockpit control panel, according to a United Kingdom investigation.
According to the report from the UK's Air Accident Investigation Branch, the coffee spill "resulted in immediate malfunction" of the impacted control panel.
The main pilot put the coffee on his tray table - but the cup was later knocked over.
The flight departed from Frankfurt airport in Germany and was scheduled to fly to Cancun in Mexico, before the incident took place.
According to a report published Thursday from a branch of Britain's Department for Transport, the mishap that followed disrupted the plane's communications systems, caused a burning smell in the cockpit, prompted pilots to use oxygen and forced the flight with 326 passengers aboard to land in Shannon, Ireland.
The hot liquid damaged an audio control panel in the cockpit, producing an electrical burning smell and smoke, an accident report revealed.
But the size of the cups used by the flight operator "made it more hard to take cups in and out of the cup holder than larger cups that have a bigger area at the top of the cup holder to grasp".
"This incompatibility generally discouraged use of the cup holder, despite the policy".
The pilots had been served coffee without lids, which was common for the route and plane operator, the report said.
It also reminded pilots to be careful with liquids, as well as supplying cups that are an appropriate size for cup holders.
A spokesperson for the airline said the diversion was a "precautionary measure due to a minor amount of smoke in the cockpit". Condor said in its statement that the airline "comprehensively investigated" the situation and has since gone over the procedures for liquid in the cockpit.
"We apologise for any inconveniences the diversion might have caused to our guests".