WASHINGTON — Human fatigue was the probable cause of the fatal crash of a tractor-trailer and a motorcoach carrying high school students in Wisconsin in 2005, the National Transportation Safety Board (NTSB) determined.

Along with its findings on the crash, the NTSB issued a call for further actions to prevent fatigue-related accidents.

“Human fatigue has been a persistent factor in far too many transportation accidents, and if anything, the problem is growing, not shrinking,” NTSB Acting Chairman Mark Rosenker said. “More needs to be done to reverse the trend so fewer of these tragic accidents come before the Safety Board.”

One potential step in reversing the trend would be to equip commercial vehicles with fatigue-detection technology, an idea that the NTSB asked the Federal Motor Carrier Safety Administration (FMCSA) to look into in the wake of the Wisconsin crash.

Just before 2 a.m. on Oct. 16, 2005, a tractor-trailer traveling westbound on a highway near Osseo, Wis., departed the right-hand lane and traveled along the earthen roadside before re-entering the highway, where it overturned and came to rest on its right side, blocking both westbound lanes.

About a minute later, a chartered motorcoach carrying members of a high school band crashed into the underside of the overturned truck.

The motorcoach driver and four passengers were fatally injured. Thirty-five passengers received minor to serious injuries. The truck driver received minor injuries.

The NTSB determined that the truck driver was fatigued and fell asleep at the wheel because he did not use his off-duty time to get enough sleep to safely operate the vehicle.

Because of the darkness, the motorcoach driver was unable to see the truck blocking the road in time to avoid the collision, the NTSB found.

The agency said that if the truck had been equipped with a system to detect fatigue, it might have prevented or mitigated the accident. Another factor that might have significantly reduced the severity of the accident, the NTSB said, is if the motorcoach had been equipped with a collision warning system with active braking.

“In this tragic accident, we can clearly see how the advanced vehicle safety technologies, some of which are already fully developed and in use, could have made a big difference here,” Rosenker said. “This Board is going to continue to be a strong advocate for the implementation of technologies that can actually prevent such terrible accidents from ever occurring.”

The NTSB added advanced vehicle safety technologies to its List of Most Wanted Transportation Safety Improvements last year. Those types of technologies include adaptive cruise control, collision warning systems, active braking and electronic stability control.

As a result of the accident, the NTSB made several recommendations to the FMCSA, the National Highway Traffic Safety Administration and Whole Foods Market Group Inc., the operator of the truck.

The recommendations and more details on the NTSB’s accident report are available at www.ntsb.gov under “Board Meetings.” The meeting date was Sept. 16, 2008.