‘Chaos’ as 'drunk co-pilot is handcuffed and escorted off' American Airlines' flight

American Airlines flight 736 from Detroit to Philadelphia was cancelled on Saturday morning

American Airlines passenger planes are seen on the tarmac (Getty Images)

Passengers preparing to take-off from a US airport have described “chaotic” scenes after the flight’s co-pilot was detained on suspicion of being drunk.

American Airlines flight 736 from Detroit to Philadelphia was cancelled on Saturday morning after the co-pilot was taken into custody when he allegedly failed a Breathalyzer test administered by airport police, CNN reports citing airport spokesperson Michael Conway.

Passengers on the aircraft at Detroit Metropolitan Airport said they saw a man being put into handcuffs on the tarmac.

A photo purporting to show the incident has emerged on Twitter.

Passenger Delany Bradley told Sky News: “First I saw a police car. About five minutes later I saw them actually taking the pilot around the side of the car and handcuffing him.

“There was a lot of scrambling. When we first got off the plane it seemed like a lot of chaos.”

Mr Conway confirmed that airport police were called to the North Terminal in the early hours of the morning in response to a pilot “exhibiting signs of being drunk”.

The man, who is understood have been born in 1965 and is from Pennsylvania, was given a further sobriety test at a local police station.

Both tests reportedly revealed he was over the legal limit for operating an aircraft.

Federal Aviation Administration guidelines state pilots cannot fly with a blood alcohol content of 0.04 per cent or above.

Authorities have not released the name of the pilot and he was later released from custody after his blood alcohol level fell, Mr Conway told CNN.

Airport police are now developing a case to present to a local prosecutor’s office.

American Airlines told ABC News: "This is a serious matter and we are assisting local law enforcement and the Federal Aviation Administration with the investigation.

"We will handle this matter appropriately as the safety and care of our customers and employees is our highest priority."

The airline apologised to any customers affected by the incident and added they were re-accommodating people whose travel plans had been disrupted.