The man who was dragged off an United Airlines flight has been identified by various media as 69-year-old Vietnamese-American grandfather, Dr David Dao.

Dr Dao is a father of five children - four of whom are also doctors - and is also a grandfather, Daily Mail said in a report on Tuesday (April 11).

Footage of him being dragged off an overbooked flight on Sunday (April 9) went viral on social media, sparking outrage at the way he was treated.

Dr Dao is a father of five children - four of whom are also doctors - and is also a grandfather, Daily Mail said in a report on Tuesday (April 11).

He studied at a medical school in Vietnam's Ho Chi Minh City, and is married to a paediatrician.

While reports also say he has a troubled past with a history of arrests, netizens have defended Dr Dao, saying that his past should have no bearing on how he should be treated.

The New York Post reported that Dr Dao was convicted of trading prescription drugs for sexual favours in 2003.

In 2004, he was reportedly convicted of multiple felony counts of obtaining drugs by fraud or deceit, the Louisville Courier-Journal said.

He was suspended from practising medicine in 2005 and resumed only 10 years later, in 2015, the Courier-Journal said.

He was also reportedly a professional poker player who made more than US$117,000 in a tournament in 2009, TMZ said on Tuesday.

However, netizens have come out in support of the passenger, saying that his past does not justify the way he was treated on the flight.

United Airlines' chief executive Oscar Munoz said in a statement on the incident that the team was "moving with a sense of urgency to work with the authorities and conduct our own detailed review of what happened".

He said the airline would also contact Dr Dao.

Straightstimes