A rail firm has been fined £1m after a man died leaning out of a train window.
Simon Brown, 24, was killed when he hit his head on a steel gantry on the side of the track while on the Gatwick Express in London in August 2016.
In May, Govia Thameslink Railway admitted a health and safety breach because a sign saying not to lean out was not displayed clearly enough.
The rail regulator has written to firms demanding "immediate action" over trains with these types of windows.
Judge Jeffrey Pegden QC, at Southwark Crown Court, said while there was a warning sticker on the door, it was "jumbled" around other notices.
"The signage around the window was confusing," he said, adding no risk assessment of the windows had been carried out.
'Tragic corporate blind spot'
Judge Pegden said there was also no-one on the train to monitor the use of the window at the time.
"This was a tragic corporate blind spot in what is otherwise a well-run organisation," Judge Pegden said.
The Office of Rail and Road said there were about 1,500 of the "droplight" windows - which allow passengers to reach through to open doors from the outside once the train has stopped at a station - in circulation on the rail network.
Director of safety Ian Prosser, who is also HM Chief Inspector of Railways, said he had written "to operators instructing them to take immediate action to prevent a similar tragedy happening again".
The accident happened on 7 August 2016 at Wandsworth Common station as the Class 442 train was travelling to London Victoria from Gatwick Airport.
The train was travelling at 61mph when Mr Brown suffered the fatal injuries.
Mr Brown, from East Grinstead, West Sussex, had been previously described by friends as a life-long railway fanatic who was working in the rail industry.
He first volunteered on the Bluebell steam railway in Sussex aged nine and was working as an engineering technician with Hitachi Rail Europe in Bristol.
The regulator said "droplight" windows were mostly confined to old InterCity trains and "charter" rolling stock, and in most cases there were four windows per carriage.
Rail firms using carriages with these windows have been asked to carry out a risk assessment of their use.
A report by the Rail Accident Investigation Branch said the sticker on the door was "cluttered" with six other notices.
The RAIB has also made recommendations telling operators to "assess the risk arising from reduced clearance outside those windows".
Simon Brown's family said in a statement: "Irrespective of the penalty imposed, we hope, as a result of our tragedy, that operating companies up and down the country will take their responsibilities to the travelling public more seriously."
Along with the fine, the firm was ordered to pay £52,267 in costs.
Govia Thameslink said it had taken the health and safety failings very seriously and pleaded guilty at the earliest opportunity.
Chief executive Patrick Verwer said: "I am very sorry for the death of Mr Brown and the deep distress this tragic loss has caused his family and friends."
Following Mr Brown's death, GTR took steps to "minimise risk" by putting hazard tape across on the droplight windows of its 14 trains that had them.
It also placed bars across the windows in such a way that it was still possible to lower the window.
The trains were withdrawn from service in 2017 across all of GTR's network.