No-one checked to ensure a teenager was securely strapped into a rollercoaster minutes before she plunged 120ft (36m) to her death, an inquest has heard.
Hayley Williams, 16, of Pontypool, was on holiday with family and friends when she fell from Oakwood theme park's Hydro ride in Pembrokeshire in 2004.
Hayley's sister told Haverfordwest coroner's court that as they queued for the ride no safety checks were made.
But the ride supervisor on the day said that visual checks were carried out.
The jury was shown a recording of Hayley boarding the ride, which seats 24 people.
Hayley was sitting in an outside seat on the last-but-one row to the rear, wearing a yellow plastic poncho to protect her from getting wet in the water at the end of the ride.
Pembrokeshire coroner Michael Howells told the jury that as the boat plunged down the chute the passenger would feel a G-force capable of flipping out anyone who was not secured.
Hayley's sister Hannah said of the checks made as they boarded the ride: "People seemed to be glancing but paying no attention whatsoever."
She added that by the time the carriage climbed to the top of the ride her eyes were closed from fear, but as it began to descend, one of her friends cried out that Hayley had fallen from the ride.
Craig Sutton Jones, who was sitting next to Hannah, said: "We were singing as we went around the u-bend. Quite a few people had their hands in the air."
He said as they were descending he realised Hayley's seat was empty and said people were in "hysterics".
Hayley fell to her death from the Hydro ride in April 2004
It was put to him that there had been "fooling around" on the ride, but he denied the claim.
Miles Mitchell, also sitting in the back row of the ride, said he was certain no-one checked the seat belts.
He said he was not aware there were belts and, as a result, rode the ride without one fastened.
The court heard that the ride was operated by a supervisor and an assistant who were responsible for ensuring passengers were strapped in before they went off.
Gareth Etches, 24, who was the ride supervisor on the day, said checks were made.
Mr Etches told the jury it was the first day he had worked on Hydro and he had received 20 minutes' training under supervision.
He said that to keep passengers safely in position "there was a seatbelt across the waist and a T-bar to secure the legs".
The operating manual for the ride said physical checks should be made to ensure both were securely in position, but Mr Etches told the court "throughout the training we were just told to ensure the belts were done up and the bars were down".
He said this was not always done physically but checks were visually made.
Mr Etches was working on the opposite side of the boat to where Hayley was sitting, so a ride assistant would have been responsible for checking whether the teenager was safely secured.
The ride drops down a near-vertical chute into a plunge pool at 50 mph
The ride assistant and senior management from Oakwood are due to give evidence when the inquest resumes on Wednesday.
Hayley had gone to the park with her parents, relatives and a group of friends in April 2004.
Hydro opened in June 2002 and was described by Oakwood as "Europe's fastest and wettest" water-coaster.
Its 24-seater boat drops down a near-vertical chute into a plunge pool at 50 mph.
Hayley fell from the ride into a shallow pool of water below.
Bystanders tried to help her but by the time paramedics arrived, her heart had stopped.
She was flown by air ambulance to Withybush Hospital, in Haverfordwest, where she was pronounced dead.
Coroner Mr Howells told the jury that they were not there to decide who, if anyone, was to blame for her death, but how she died.