A 78-year-old woman was dragged into a tube tunnel when her bag became stuck in the train doors – when the oblivious driver fell into “automatic mode”.
The woman suffered multiple bone fractures when she was pulled 100 metres along a platform and into a tunnel, a Rail Accident Investigation Branch report said.
Investigators believe the driver may have suffered “inattentional blindness” caused by his repetitive work.
The woman was pulled by the train for 16 seconds before it finally stopped, the investigation found.
She spent one month in hospital after the accident on the Central Line platform at Notting Hill station, in west London, on January 31.
A report said: “As the train moved off, the passenger was unable to free herself.
“Within four seconds, she had fallen down and was being dragged along the platform.
“Someone on the train who was next to the door tried to open the doors by hand, but was unable to do so.”
The report said the public expect doors to reopen if they are obstructed.
But the trains’ systems, which alert the driver, only detect items more than 6mm thick.
It added: “As the doors were closing, she had her bag ahead of her, which swung the bag forwards into the carriage.
“The doors then fully closed, trapping the bag along its top edge, just below the handles.”
The train moved for ten seconds before the emergency brake activated and it took a further six seconds to come to a stop.
The woman was dragged 15 metres into the tunnel and it took more than one hour for her to be rescued, the report said.
She is still said to be recovering from the ordeal.
A phenomenon called inattentional blindness was given as a possible reason.
The report said: “A phenomenon known as ‘inattentional blindness’ can occur in this type of visual search task when actual targets (ie people trapped in doors) are relatively rare or unexpected.
“Research in this field shows that even for trained and experienced operators, about one-third can fail to notice a target, despite the fact that they may be looking directly at it.
“The train operator had never been involved in such an incident before, although he had experienced several false alarms with other objects (eg newspapers) trapped in doors.
“The task therefore fits the criteria for inattentional blindness in that targets are relatively rare compared to non-targets.”
New computer systems replacing manual tasks was given as a reason for the phenomenon.
The report said: “The RAIB has made five recommendations and one learning point, all addressed to London Underground.
“The recommendations concern the detection of objects by the train’s door systems, how the design of the task, equipment and training can influence train operators’ attention and awareness, and the use of emergency stop facilities on platforms.
“While there is no evidence that the train operator was impaired by drugs or alcohol, the learning point concerns the importance of following procedures for drug and alcohol testing where relevant.”
By Ben Gelblum and Lewis Pennock