On June 2, 2018, a serious accident occurred on The Joker roller coaster at Six Flags Discovery Kingdom in Vallejo, California. The ride, which features a flying launch and high-speed maneuvers, experienced a rollback during testing, causing the train to collide with the brake run and come to rest partially inverted.
The incident injured several riders and prompted scrutiny from regulators and the public. This article reviews the event, key facts, and ongoing implications for park safety and maintenance.
| Attribute | Details | Impact | Reference |
|---|---|---|---|
| Date | June 2, 2018 | Late morning during testing | Regulatory and media timeline |
| Location | Six Flags Discovery Kingdom, Vallejo, CA | Triggered park ride suspension | Operations log |
| Attraction | The Joker – Floorless Coaster | Launched coaster with complex launches | Manufacturer records |
| Injuries | Several riders, mostly minor | Medical response and transport | Incident report summary |
| Root Cause | Premature rollback into brake run | Procedural and hardware review | Investigation findings |
Ride System and Mechanical Details
Launch and Braking Configuration
The Joker at Six Flags Discovery Kingdom combines linear synchronous motors with a traditional chain lift, enabling rapid acceleration and complex layouts. On the day of the accident, the train experienced an unexpected rollback during a test run, striking the mid-course brake run and overturning part of the train.
Immediate Response and Ride Closure
Following the collision, the ride was immediately closed for investigation. Emergency crews evaluated riders for injuries, and park staff coordinated with local authorities to document the event and assist those affected.
Safety Protocols and Incident Response
Testing Procedures and Operational Checks
Amusement ride testing typically includes multiple runs at reduced speed to validate sensors, brakes, and launch systems. The rollback suggested that either sensor data or brake application did not perform as intended during this test sequence.
Regulatory Oversight and Industry Standards
The California Division of Occupational Safety and Health reviewed the accident and issued findings against Six Flags. Inspectors focus on mechanical integrity, maintenance records, and operational procedures to determine compliance with industry standards such as ASTM F24 committee practices.
Park Operations and Communication
Guest Notifications and Service Adjustments
The park communicated ride closure through signage, staff, and digital channels, while adjusting throughput in nearby attractions. Operations teams coordinated with maintenance to prioritize safety checks before any return to service.
Maintenance Culture and Continuous Improvement
Long-term operations require robust maintenance planning, component lifecycle tracking, and proactive inspections. The incident encouraged a review of test protocols, documentation, and cross-department coordination to reduce similar risks.
Investigation Findings and Outcomes
Regulatory Conclusions and Corrective Actions
Investigators identified missed intervals in maintenance and procedural gaps that contributed to rollback. Six Flags implemented additional sensors, revised test sequences, and enhanced staff training as part of corrective action plans.
Key Takeaways and Recommendations
- Review and validate test procedures for rollback scenarios on launching coasters.
- Ensure brake system maintenance intervals align with manufacturer and regulatory guidance.
- Enhance data logging during test runs to capture subtle anomalies before guest loading.
- Maintain clear communication with guests and regulators during incident investigation and recovery.
- Invest in staff training focused on emergency response and ride system diagnostics.
FAQ
Reader questions
What exactly happened on The Joker at Six Flags Discovery Kingdom in 2018?
During a test run on June 2, 2018, the train rolled back and struck the brake run while in a partially loaded configuration, causing the train to partially invert and injuring several riders.
How many people were injured and how serious were their injuries?
Multiple riders sustained minor injuries, with medical personnel treating and transporting affected guests, while overall severity remained relatively low compared to historical coaster incidents.
Did investigators identify a single root cause for the rollback?
Findings pointed to a combination of sensor timing and brake application issues, compounded by test procedures that did not fully account for rollback scenarios in that configuration.
What changes did Six Flags implement after the accident?
The park updated test protocols, added redundant monitoring for brake engagement, and strengthened maintenance documentation and staff training to reduce similar risks.