A man has spoken out about the "violent death" of a 24-year-old on a flight from Portugal to Ireland.
The victim, believed to be a Brazilian man, suffered an apparent seizure and collapsed, forcing the Aer Lingus service from Lisbon to Dublin to divert to Cork Airport on Sunday evening.
A passenger who attempted to restrain him was bitten on the arm.
A post-mortem examination is to be carried out to determine the cause of death.
A Portuguese woman in her 40s was arrested on suspicion of drugs offences after the flight landed following the discovery of a quantity of amphetamines. Gardai are investigating if she was travelling with the dead man.
Passenger John Leonard, from Cork, said the man appeared to suffer a seizure, after which he had to be restrained at the back of the plane. The victim collapsed a short time later.
"[It was] horrible," Mr Leonard added. "I would say a very violent end. To die that way in the back of an airplane. It's not right. It was not pleasant at all."
Mr Leonard told a radio station in the Republic that two nurses and a doctor tried to help the victim after the captain asked for assistance.
"After that it got worse, I would say - his seizure seemed to get worse," Mr Leonard said. "He was on the ground shaking violently.
"The noise he was making was like something I have never heard before.
"It's not something you'd hear every day. It was like deep anguish. [That is] the best way I could describe it - very, very troubled. Not screaming in the sense of you know you'd hurt yourself or something, just guttural, from deep within him."
The other 167 passengers on flight EI485 were kept on board for two hours after it landed at 5.40pm before being interviewed by gardai and offered bus transfers to Dublin.
Mr Leonard said passengers remained "extraordinarily calm" throughout the incident but had been left in a state of shock.
Aer Lingus described the incident as a "medical emergency".
The post-mortem examination is to be carried out in an attempt to establish if the man suffered a seizure, had an underlying medical condition or if there was another reason for his condition.
The arrested woman was last night being questioned at Togher Garda Station in Cork city.