The extinction clock is accelerating on the Knott’s Xcelerator roller coaster, which is quickly becoming an endangered species as the granddaddy of an aging class of thrill rides watches better-known kin drop like flies.

Three rides similar to the Xcelerator, all younger than the Knott’s Berry Farm coaster that debuted in 2002, are currently out of commission: Top Thrill 2 (2003), Kingda Ka (2005) and Formula Rossa (2010).

The first Intamin Accelerator coaster ever built, Xcelerator reopened in November 2023 after spending two years on the disabled list while getting a new hydraulic launch system installed.

Xcelerator speeds from zero to 82 mph in 2.3 seconds with the assistance of the hydraulic launch, according to Roller Coaster Database. The Xcelerator trains quickly transition into a 205-foot-tall vertical top hat element before sending riders plunging downward on a relatively short ride covering 2,200 feet of track in a minute.

Over the past decade, three Intamin Accelerator coasters have been relocated, one has been closed and two are “standing but not operating” — Roller Coaster Database’s version of the disabled list.

“Over time, I believe we’ve seen just about every one of these coasters shut down for an extended period of time to repair the launch systems,” Screamscape’s Lance Hart said.

Six Flags announced in November that Kingda Ka would be removed from its Six Flags Great Adventure park in New Jersey and replaced by a record-breaking launch coaster in 2026.

“Kingda Ka has delivered more than 12 million rides since 2005,” Six Flags said in a statement.

“What was cutting edge roller coaster technology 20 years ago has been surpassed by more modern advancements.”

Ferrari World’s Formula Rossa and Cedar Point’s Top Thrill 2 are both eventually expected to reopen.

Formula Rossa has been closed since January 2024 to repair the launch system — a process that can take a year or more, according to Screamscape.

Cedar Point closed Top Thrill Dragster for the entire 2022 and 2023 seasons after a metal piece flew off the ride and seriously injured a woman waiting in the attraction queue in 2021.

The hydraulic launch system of the rechristened Top Thrill 2 was replaced with a Zamperla electromagnetic unit in May — but the ride only operated for about a week before it was closed again due to mechanical issues.

The Intamin Accelerator coasters employ a hydraulic launch system with a rapidly spooling cable that pulls the trains to speeds ranging from 80 to nearly 150 mph. Intamin produced 14 of the lightning-fast rides between 2002 and 2010.

“These systems were a bit finicky, heavy on the maintenance side,” according to Screamscape. “It was typically a matter of ‘when’ the launch system was going to crap out unexpectedly. The repair process was always a lengthy and expensive one, so it was no surprise when Intamin decided to retire the launch system for good.”

Zamperla removed the old hydraulic launch systems and installed new magnetic launches on Top Thrill 2 as well as ThunderVolt at Canada’s Playland.

Ferrari World removed the Formula Rossa hydraulic launch system over the summer, according to Screamscape.

Screamscape estimates Xcelerator’s new hydraulic launch system should last eight to 13 years.

Knott’s paid $13 million for the Intamin extreme coaster in 2002, according to Roller Coaster Database.