American Airlines flight AA87 to Chicago was delayed at Heathrow yesterday morning when it became clear that the pilot was drunk, international media reported.

Airport security staff were sufficiently concerned by the pilot's behaviour to alert police officers as he was about to board the Boeing 777, where 204 passengers were waiting to cross the Atlantic.

The pilot, believed to be Joseph Crites, was arrested by police officers after he failed a breathalyser test. A replacement was found and the 10.15am flight took off an hour and 15 minutes later.

American Airlines said today: "An American Airlines pilot was arrested at Heathrow yesterday having failed a breathalyser test. Police had been called by airport staff working at the security control post.

"Our primary concern is for the safety and comfort of our passengers and crews. The company has strict policies on alcohol and substance abuse and holds its employees to the highest standards. Employees at all levels of the company are not allowed to be on duty while under the influence of drugs or alcohol and regular screening is carried out."