The 1986 Mindbender accident is the only disaster on the list that happened indoors, but that doesn't make it any less tragic. The ride, said to be the largest indoor triple-loop coaster, featured steel construction and a four-car train. It was the main attraction of the West Edmonton Mall's amusement park, Fantasyland [source: Franklin].
It was June 14, 1986, just one day after an Alberta province safety inspector declared the ride safe. The train slid around a turn at 60 miles per hour (96.5 kilometers per hour), gaining momentum for the first of the three loops. Before it got there, though, the rear car began to fishtail. It proceeded through the first two loops but derailed as it approached the third loop, stalling at the top and sliding backward into a concrete column. Three riders perished and at least 15 were injured, one seriously [source: UPI].
Investigators determined that missing bolts in a wheel assembly caused the accident. The ride was subsequently closed for several months while the operators made safety improvements to the cars including the installation of anti-rollback mechanisms, seatbelts and headrests. Additionally, the number of seats per car was reduced from 16 to 12, and the number of cars in the train was reduced from four to three. Since then, the amusement park's name has changed from Fantasyland to Galaxyland, and the Mindbender has, thankfully, been accident-free [source: Franklin].