A tram which flipped onto its side, killing at least seven people, failed to brake in its usual place at a bend on the track, according to a passenger rescued from the disaster.
Royal Navy veteran Kevin Snow, 57, was on his way to work in central London when the busy service overturned early on Wednesday, injuring him and around 50 others.
The father-of-seven from Barnsley, south Yorkshire, said that the service, which he had been using regularly while working in London, failed to slow down at its usual point coming out of a tunnel between the Lloyd Park and Sandilands stops.
He said: "Usually as you come out the tunnel you feel the brakes, but I didn't seem to at all. I thought, he should be braking in a minute.
"The next thing I knew we were on our side. Everyone was screaming and shouting, a lot of people were injured - lots couldn't move."
He said the tram slid for between eight and 10 seconds before coming to a halt.
Investigators have said they believe the vehicle was travelling at a "significantly higher speed than is permitted", and are probing whether the 42-year-old driver, who has been arrested on suspicion of manslaughter, may have fallen asleep.
The deadly crash is believed to be the first tram crash in which people died in more than 55 years.
Snow spent 15 years in the Navy before becoming a ceiling fitter. He is staying with family in New Addington, where he grew up, while working on a site in Shaftesbury Avenue in the West End.
He said passengers had struggled to reach emergency exits in the tram which were on the roof because the service had slid onto its side.
He said: "It seemed like forever that everyone was trying to get out, but we couldn't find a way out. All I could think about was if no one called the emergency services, could another tram hit us?"
He described how the "brilliant" emergency services eventually smashed the windscreen to rescue them, moving them to a second tram to administer first aid.
He was taken to Croydon University Hospital with a badly bruised shoulder and back and later discharged. He added that he plans to go to work on Thursday.