A British Airways plane. File photo: AP Photo/Matt Dunham.

Johannesburg - Passengers and crew members on a flight from Cape Town to Johannesburg were left in shock after a fellow passenger assumed to be sleeping turned out to be dead. 

The incident happened on Wednesday afternoon on a British Airways flight from Cape Town International Airport to OR Tambo International Airport. 

Police spokesperson Lieutenant Colonel Katlego Mogale confirmed the incident to IOL and explained that her death was discovered when everyone was disembarking.

"Everybody assumed she was asleep, and when the flight stopped here (OR Tambo), everybody disembarked and they said 'mam' and mam was not waking up. They called the paramedics, paramedics [then] certified her dead. 

"Now we've opened an inquest to find out how she died, what happened."

Mogale said the woman, a Chinese national, was fine at the time of boarding in Cape Town and needed no assistance boarding the flight. 

Mogale was unable to confirm on which airline the incident happened but spokesperson for British Airways William Smook confirmed it happened on one of their flights from Cape Town. 

"We are saddened to confirm that one of our customers passed away aboard BA6406, scheduled from Cape Town International Airport to OR Tambo International Airport on Wednesday.

"A medical emergency was identified upon descent and emergency medical personnel boarded the aircraft as soon as it landed in Johannesburg and took over from our crew, who are trained and equipped to deal with medical emergencies onboard.

"Our thoughts and prayers are with the customer’s family and friends, as well as those who have witnessed this tragic event," Smook said.