Transport union bosses are demanding a full investigation after the doors of a packed tube train opened between stations as it was heading at speed towards Heathrow Airport.
The doors of the Piccadilly Line train from central London opened between Hounslow West and Hatton Cross stations on Sunday afternoon, said the RMT Union.
It added that the seriousness of the incident was reinforced by the fact that a baby in a pushchair was close to the doors that opened.
Fortunately, the train driver was alerted to the fault by a signal in his cab and stopped the train to ensure the safety of the passengers.
RMT is demanding a top level inquiry looking at all aspects of the incident and producing recommendations to avoid a repeat.
It says the incident raises questions about the reliability of the aging fleet on the Piccadilly Line, which is now 40 years old and not due for replacement for another decade.
"It also rams home the challenges of maintaining aging fleet and infrastructure against a background of cuts to schedules and staffing, a point reinforced by the threatened cuts package currently being drawn up by tube bosses," the union said in a statement.
RMT general secretary Bob Crow added: "Sunday’s incident on the Piccadilly Line must serve as a wake-up call to tube bosses and (London Mayor) Boris Johnson.
"Once again, it was the sharp and decisive action of the driver in the cab which prevented a possible disaster on a packed tube train travelling at speed. Anyone who continues to press for the policy of driverless operation should look at this incident and hang their heads in shame.
"Clearly there now needs to be a formal and detailed investigation conducted at the highest level as this is not the first time our members have reported door malfunctions on the aging Piccadilly Line fleet."
