Investigators said CCTV footage appeared to show Jaiden walking towards the crossing, looking ahead and down at a “glowing object” almost certain to be the illuminated screen of a phone in his hands, with his coat hood pulled over his head.
Analysis of his phone suggests a video clip was playing at the time of the accident.
After seeing Jaiden start to cross the railway, the driver sounded the horn and applied the emergency brake. He looked up in response but did not have time to move clear before the train reached the crossing.
The RAIB said the accident happened because Jaiden did not perceive the risk associated with the train, probably because he was distracted by his phone.
Jaiden, a pupil at the nearby Riddlesdown Collegiate secondary school, had regularly used the crossing on his way to and from school since starting there in September 2024, the RAIB said.