London - A spilt cup of coffee melted a plane cockpit’s instruments and forced a flight to turn back halfway across the Atlantic Ocean.
With 337 people on board, the Mexico-bound flight made an emergency landing in Ireland, having taken off in Germany.
The drink burnt part of a control panel in the cockpit, making it difficult for the crew to communicate, an accident report said.
Smoke and the smell of electrical burning then filled the cabin of the Condor airline flight from Frankfurt to Cancun.
That left the flight crew forced to breathe through oxygen masks as the plane was diverted to Shannon airport.
The Air Accidents Investigation Branch said the "serious incident" in February caused the "immediate malfunction" of an audio control panel. It became so hot that one of the buttons on the panel started melting. A second control panel failed minutes later.
Several hours into the flight, the pilot was served a cup of coffee without a lid which he placed on his tray table. The unnamed 49-year-old knocked the cup over while he was carrying out navigational checks.
Most of the drink fell into his lap, but some fell on to the controls. The coffee was quickly mopped up but the spillage made it difficult to contact flight controllers and make announcements on board.
"The unit became very hot and failed and [another unit] became hot enough to start melting one of its buttons, and failed," the report said. "A small amount of smoke was observed coming from the [first unit]." The fumes did not cause any injuries to the crew or passengers on board.
The cups used by Condor were too small to get in and out of cup holders easily, so pilots often left them on tables in front of them.
The airline has now ensured that cup lids are provided, the report concluded, saying that "appropriately sized cups" should be used.
Condor apologised for the diversion, adding that it had reviewed the procedures of liquids in the cockpit and reminded its crew of "careful handling".Daily Mail