A pilot who was due to fly a plane from London to Hong Kong was arrested at Heathrow Airport on suspicion of possessing knives.
The Cathay Pacific flight was severely delayed following a "crew-related incident" concerning items found in the pilot's hand luggage.
Metropolitan Police confirmed they were called to a staff search area at Heathrow Airport on 18 April.
A police spokesperson said: "Officers attended and subsequently a member of the flight crew, a man, was arrested on suspicion of possession of an offensive weapon in a public place and possession of a knife blade/sharp pointed article in a public place.
"He was taken into custody at a local police station where he was later bailed to return in mid-May pending further inquiries. The CID at Heathrow airport is investigating."
A spokesperson for Cathay Pacific said: "Cathay Pacific can confirm that CX254 was delayed due to a crew-related incident concerning some items found in the pilot's hand luggage.
"At no point were passengers or staff put at risk. Given timings, Cathay Pacific were unable to organise a relief crew and therefore passengers experienced an overnight delay. Cathay Pacific takes this very seriously and is liaising with the relevant authorities."
The flight carrying 262 passengers on broad eventually departed on the afternoon on 19 April.