A panicked stewardess ordered an unnecessary emergency evacuation from a plane before take off, resulting in 10 people being injured while sliding down escape chutes onto the runway.
The engine of the A320-214 jet travelling to Vienna suddenly failed while it was beginning its journey down the tarmac at London Stansted Airport at 8.20pm on March 1 last year, according to a report by the Air Accidents Investigation Branch (AAIB).
Cabin crew were told to await further instructions by the pilot.
However, a senior flight attendant, who was scared by a banging noise made by the failed engine, ordered an emergency evacuation.
The six exit doors were opened and a staff member announced "evacuate, evacuate, evacuate" over the plane's intercom system - prompting panic among passengers.
Escape chutes were automatically inflated and the 169 people on board were told to slide down onto the tarmac.
Ten passengers had to be treated for injuries following the "needless" evacuation.
Most suffered cuts, bruises and sprains, but two were taken to hospital and later discharged.
Some later complained to Laudamotion, the budget Austrian airline which operated the flight, that they were being treated for post traumatic stress disorder.
The evacuation led to the runway being shut for two and a half hours, with 13 incoming flights having to be diverted.
Passengers had been exposed to a risk of "serious injury", according to the AAIB report, as one of the plane's engines was still operating when they disembarked.
This could have resulted in them being either sucked towards it or being hit by the 65mph gusts blowing out of it.
Several passengers who exited beside the right wing said they were knocked over by the air coming from the engine and their possessions had blown away.
The evacuation was also hampered by passengers trying to take their luggage with them down the chutes, which could have torn them.
The senior flight attendant said she did not hear the pilot's intercom message to cabin crew telling them to await further instructions.
She may not have been "well prepared for her role in the emergency" due to deficiencies in her training, the AAIB report said.
The report concluded: "As a result of the engine failure and subsequent rejected takeoff, the Senior Flight Attendant commanded an emergency evacuation that was not necessary in the circumstances.
"This was probably the result of a combination of factors that heightened her emotional response to the event and affected her decision making.
"The factors included inexperience as a flight attendant, weaknesses in her training and communication difficulties during the event.
"As a result of the flight crew not being consulted before the evacuation was commenced, the right engine remained running for the first few minutes of the evacuation.
"This led to an increased risk of serious injury to those passengers that evacuated on the right side of the aircraft. Indeed, several passengers sustained minor injuries having been blown over by the exhaust.
"During the evacuation several passengers hindered the evacuation by taking their cabin baggage with them. While some were removed by the flight attendants at the supervised exits, this was not possible at the overwing exits."
The report said that the airline had improved its training for cabin crew as a result of the incident.
It had also amended its flight safety manual "to instruct the Flight Attendants to attempt to establish communications with the flight crew to check that an evacuation is safe and necessary before commanding it independently."
Laudamotion said in a statement: "Laudamotion welcomes the AAIB report on an engine failure at London Stansted which acknowledges Laudamotion’s subsequent safety actions."