Chaos broke out aboard a British Airways flight when a passenger stabbed a man with a wine bottle that had been purchased on board.
The victim was left needing 12 stitches after trying to intervene when a fight broke out between two men at 33,000ft.
The drama took place on Monday as BA flight 2159 made its way from Gatwick to St Lucia.
A man from the Caribbean island is said to have attacked a man and his family.
As the fight escalated, another Saint Lucian intervened in an attempt to make peace.
But the peacemaker, who suffers from diabetes, sustained a cut requiring immediate attention from a nurse on the flight.
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The attacker, who witnesses say was wearing a bucket hat and glasses, is said to have smashed a glass bottle in the galley, spraying shards throughout the area.
He then marched along the aisle before swinging the broken bottle at the passenger he had been arguing with.
Crew and other travellers attempted to separate the two, but not before the unarmed peacemaker sustained a considerable gash that saw blood spattered across the cabin.
The pilot radioed ahead to Saint Lucia officials, and when the Boeing 777 touched down at 1.55pm local time, the man who sustained the injuries received further medical attention at St Jude Hospital.
Passenger Nichola Pierre said: "I was onboard this flight, and these guys were drinking and giving jokes with each other before this occurred.
“One man got stabbed in the torso and the other guy in the back of the head before another gentleman and myself were able to calm down this guy who purchased a duty-free wine bottle which he used to commit the act.
The man was arrested on landing.
A spokesman for St Lucia police said: “We are looking into this with immediate effect. This is a very serious matter which occurred on a plane. This is very serious indeed.”
The identities of the passengers involved have not yet been released.
A British Airways spokesperson said: "We’re shocked that anyone would act in this way and are grateful to our highly trained cabin crew and the customers who supported them in handling this difficult incident.
“We want to assure customers that this behaviour will never be tolerated, and we will always take the appropriate action.”
