The seven victims of a tram crash in Croydon were thrown out of windows as they shattered, investigators said.
It added the brake was applied two and a half seconds before the crash, suggesting the driver "lost awareness".
A total of 70 passengers were on board in November, rather than 60 as originally believed, it showed.
The report found the tram was travelling at 46mph - faster then the 43.5mph initially thought - before it crashed in a 13mph zone near the Sandilands Junction area of Croydon.
The RAIB's second interim report said: "Of the seven passengers who died, one was found inside the tram; two were found partially inside the tram; three were found underneath the tram; and another was found on the track close to the tram."
The brake would have had to have been applied as the tram entered the last of three tunnels approximately 180 metres ahead of the junction, which was a left turn, in order to slow sufficiently to 13mph, the report indicated.
But the RAIB said the late application of the brake and the "absence of emergency braking" suggested tram driver, Alfred Dorris - the only member of staff on board - had "lost awareness" that he was approaching the 13mph zone.
The seven people killed were Dane Chinnery, 19, Philip Logan, 52, Philip Seary, 57, Dorota Rynkiewicz, 35, and Robert Huxley, 63, all from New Addington, and Mark Smith, 35 and Donald Collett, 62, both of Croydon.
A further 51 people were taken to hospital, with eight of them suffering injuries described by London Ambulance Service as serious or life-threatening.
London's Transport Commissioner Mike Brown, said Transport for London's (TfL) thoughts remained with "all those affected by the tragic tram derailment".
TfL added in January it installed chevron signs at four sites with significant bends including Sandilands to provide an additional visual cue for drivers.