The accident at Alton Towers in which four people were left badly injured has shocked the nation, but although incidents on rollercoasters at theme parks are rare, they are not unknown.
The £18 million ride The Smiler where the crash took place was temporarily closed in November 2013 after plastic guard wheels came loose and hit front-row riders.
The 14-loop rollercoaster, which took more than eight months to build, was shut for four days in July that year after a piece of track became dislodged, and was closed again for five days the following month because of another technical issue.
In July 2011, a number of people on a ride at M&D's theme park at Strathclyde Country Park, Motherwell, Lanarkshire, were stranded for more than eight hours when it came to a halt 60 feet above the ground.
In June 2006, firefighters had to rescue eight children and four adults trapped 40ft above the ground on the Terror Rack ride at the Pleasure Island park in Cleethorpes, Lincolnshire. It took the fire crews about an hour and a half to bring the people down to the ground after a safety device kicked in and halted the attraction.
A 32-year-old woman and 30-year-old man were taken to Glan Clwyd Hospital for treatment to chest injuries. Two other people received minor injuries and did not need treatment.
The previous year, a 16-year-old girl plummeted to her death from a ride at Oakwood theme park near Tenby in west Wales.
Hayley Liane Williams, of Pontypool, south Wales, died after falling from the Hydro Ride.
She plunged 100ft from the ride on April 15 2004. Swansea schoolboy Martin Rothwell, aged 10 at the time, was hit in the head and injured by the teenager as she fell past him. Safety changes were later made to the ride.
In November 2006, a French firm was found guilty of breaches of health and safety law after the death of a 20-year-old student on a rollercoaster.
Durham University student Gemma Savage died when two cars collided on the Treetop Twister ride at the Lightwater Valley theme park, near Ripon, North Yorkshire, on June 20 2001.
Paris-based Reverchon Industries SA, which manufactured and supplied the ride, was found guilty at Leeds Crown Court of two charges of failing to ensure its safe design and construction, and failing to give information necessary to ensure the ride was safe when open to the public.