The National Transportation Safety Board (NTSB) determined that the probable cause of the Nov. 28, 2008, accident at Miami International Airport, involving an automated people mover train, was the installation by Johnson Controls Inc., maintenance technicians of a “jumper wire” that prevented the overspeed/overshoot system from activating to stop the train when the crystal within the primary program stop module failed.

"We have seen in this accident and other investigations that too often there is a lack of crucial safeguards," said NTSB Chairman Deborah A.P. Hersman. "The state did not oversee the safety of the people mover. Finally, at the federal government level, no agency has authority for the safety oversight of people movers, much less any fixed-guideway or transit operations."

On Nov. 28, 2008, a three-car automated people mover train operating on a fixed guideway at Miami International Airport  failed to stop at the passenger platform and struck a wall at the end of the guideway. As a result of the accident, a technician and five passengers on the train were injured.

The NTSB investigation also determined that the following factors contributed to the accident:

• The failure of Johnson Controls Inc., to provide its maintenance technicians with specific procedures regarding the potential disabling of vital train control systems during passenger operations.

• Ineffective safety oversight by the Miami-Dade Aviation Department.

• Lack of adequate safety oversight of such systems by the state of Florida.

• Lack of authority by the U.S. Department of Transportation to provide adequate safety oversight of such systems.

As a result of this accident, the NTSB issued five new safety recommendations to the U.S. Department of Transportation, the 50 States and the District of Columbia, Miami-Dade County and Johnson Controls Inc. The NTSB also reiterated a previously issued recommendation to the U.S. Department of Transportation.

A synopsis of the NTSB report, including the probable cause, findings, and a complete list of the safety recommendations, is available at http://www.ntsb.gov/news/events/2011/miami_fl/index.html. The NTSB's full report will be available on the website in several weeks.