A drunken man prompted the diversion of an aircraft when he reportedly tried to kick the windows out on the plane - causing a woman to drop her baby.
The unplanned stop at around 4.30pm local time occurred after the rowdy passenger, believed to be a Brit, had a meltdown mid-air.
The man, who was travelling with his female partner and child, only stopped his mid-air rampage when he was subdued by US Marines onboard the flight.
The outburst continued to escalate as the flight went on, with the boozed-up passenger kicking off with flight attendants at least three times at different points of the journey.
Onlookers claimed the man eventually tried to kick out the windows of the Boeing 787 Dreamliner.
A mum caught up in the commotion dropped her baby, leaving the child with major injuries, according to The Sun.
The cabin crew and pilot subsequently decided to land the plane, and the man was hauled off by Salt Lake City Police Department officers and US Customs officers.
An eyewitness said: "There was an altercation involving the man about an hour into the flight. He was a British guy.
"It took a good while to get him to sit back down and resolve it.
"Then a few hours later it happened again and I thought to myself ‘This may not end well’.”
The man went to sleep shortly after the initial brawl, but woke up “ready to go again”, the witness said, claiming that’s when he started getting physical.
At this point, two US Marines “piled in” on him and handcuffed him in the back of the plane.
According to the source, the man then started “whining” that he could not feel his fingers, after he was restrained by officers.
The Marines worked for some time to subdue the man before they decided to land the plane.
The witness said it was “intense” for a while and they got upset as it was the third time it had happened.
The disruptive passenger exited the aircraft with his family in Salt Lake City, leaving the plane to carry on to Los Angeles.
The US Attorney was expected to file formal charges on Wednesday.
A US law enforcement source said that a passenger on board the plane became unruly and fought several passengers while attempting to move toward the cockpit.
Marines eventually got the man under control and handcuffed him, before diverting to Salt Lake City for police to enter the plane and take him into custody.
According to passengers on the flight, the atmosphere was already tense before take-off, due to the chaos at Heathrow.
Travellers were "agitated", one person said, after being stuck in huge queues at the major airport.
