The pilot of a Boeing 747 was forced to make an emergency "mayday" call after cockpit alerts warned him of a potential fire on board.
The aircraft was flying over the Irish Sea when a fire warning sounded from the deck, where 390 cows were being transported.
However, technicians later found no evidence of fire, and concluded that the alarms must have been tripped by heat from the cattle.
The body temperature of cows is typically 38.6C, slightly higher than that of humans. However, cows also emit 100-200 litres of methane per day, in the form of flatus. The crowded conditions, plus the presence of noxious gas emissions, may have raised the temperature on board.
The Civil Aviation Authority has revealed that last year there were 186 maydays and 1,076 fewer urgent pan-pan calls, following a Freedom of Information request by the Sunday People.
Flocks of birds hitting jet engines and staff illness also caused crews to make emergency calls.