© Flightradar24Flight AA904 was travelling from Rio de Janeiro to Miami around 11pm Thursday when it diverted to Brasilia (shown on map above)
Flight 904, which left Rio de Janeiro at 10.16pm Thursday heading for Miami, was diverted to Brasilia after four people - including three members of staff - complained of lightheadedness, the airline confirmed in a statement to Daily Mail Online.
'The aircraft landed safely at Brasilia at 12.37am and was met by paramedics who evaluated the passenger and crew members. None requested further medical attention,' an American Airlines spokesperson said.
'Our maintenance team is currently inspecting the aircraft and performing a thorough maintenance check.'
The emergency landing happened the day after an American Airlines flight to Los Angeles was forced to return to London's Heathrow Airport after around 15 people on board fell ill.
Although the two grounded flights involved air planes of similar models, airline officials said they 'do not want to speculate on whether [the two incidents] are linked' until investigations have been completed.
One passenger on the Miami-bound flight told Daily Mail Online she saw people 'pass out' from the mystery illness before the plane landed.
'We are currently still in Brasilia where we made an emergency landing because crew members and passengers passed out and became unwell,' the woman wrote in an email.
'It sounds exactly like what happened on the other flight with us not being allowed off the plane for two hours.
'As you can imagine frustrating chaos followed and most people are stuck here for 48 hours. One of the crew said something about oven cleaner reacting badly.'
Another passenger, Xime Etchart, wrote on Twitter early Friday morning: 'Emergency landing in Brasilia from Rio to Miami. We're all still waiting for an update on when we are flying back...'
In a second tweet, Etchart wrote she'd been stuck in Brasilia for six hours with 'no food, no room, no help at all.'
The Miami-bound Boeing 777, which carried 203 passengers and 14 crew members, was of a similar model to the one that was forced to divert back to London Heathrow following a 'medical emergency' on Wednesday.
The captain on the flight from London to Los Angeles made the decision to turn around after increasing numbers of people on-board became ill.
© Eric WinterA paramedic from London Ambulance Service, Hazardous Area Response Team, carrying out tests on the air inside the cabin of a flight forced to turn back to London over the Atlantic after crew starting fainting
Comment: According to a doctor who was a passenger on flight AA109 from London Heathrow to Los Angeles, two flight attendants reported 'a slight electrical or burning smell' on board.
Last year other incidents on aircraft such as, "burning electrical or smoke", "odor of fumes" in cabins and smoke filled cockpits, also forced emergency landings.