The incident, which left a number of passengers terrified and in tears, occurred during an Aer Lingus-operated transatlantic flight in August 2012.

At one point, the pilot told passengers he was considering diverting the flight due to the disturbances.

The Federal Aviation Authority carried out an investigation into the incident, while Aer Lingus confirmed an internal inquiry was undertaken.

A complaint made by passengers Matthew Jacobs and Bethany Grabiec to the FAA, and seen by the Irish Examiner, was backed up by one of the flight attendants on board who was horrified by the behaviour of her colleagues.

In the complaint, Mr Jacobs said when he asked to speak to the purser (chief flight attendant) after hot tea was spilled on his wife, the flight attendant was “abusive, threatening and angry”, and “appeared to be quite intoxicated”.

“When another passenger tapped Mr X on the arm to tell him he was out of line, the purser threatened to have the other passenger and several of us arrested,” Mr Jacobs said.

The attendant’s report for Aer Lingus stated: “X then said ‘You are going to jail’. He charged through mid-cabin shouting loudly that the man was going to jail.”

Mr Jacobs also describes how another flight attendant who “smelled strongly of whiskey” asked him to keep quiet. He was told by Mr Y that “the law was on the side of the flight attendants after September 11”.

“About half an hour later, Mr Y summoned me to one of the galleys, where he and I were alone. He smelled strongly of whiskey,” said Mr Jacobs.

“He told me that as long as I promised to keep quiet and not let the matter go beyond the flight, my wife and I would not be arrested upon arrival. He then told me that the passenger who had tapped Mr X on the arm would be arrested upon arrival for assaulting a flight attendant.”

Asked whether he felt physically threatened, Mr Jacobs told the Irish Examiner: “Most certainly.”

After all of the flight attendants were interviewed by the captain, the Irish Examiner understands that a fax was forwarded to Dulles to request that the attendants in question be tested for alcohol and drugs.

A series of questions were put to Aer Lingus on the nature of the investigation, whether or not the crew were tested for alcohol and drugs on landing and if they operated the final flight on that route after the incident.

It confirmed an incident took place on the flight. “The incident was the subject of an internal investigation. As a policy we do not disclose the outcome of such internal investigations.”

The FAA investigation stated that it contacted the pilot who stated that “no evidence emerged during the Aer Lingus investigation, to support the complaint”.

“Therefore, information received from the company was insufficient to support allegations from the complainant,” stated the report.

Efforts were made to contact both attendants at the centre of the complaints.

One responded seeking further details on the complaints made against him. He failed to respond when these details were supplied.