WASHINGTON, D.C. --- The National Transportation Safety Board (NTSB) has sent a letter to Whole Foods Market Inc. recommending that the company implement a comprehensive education program to ensure that employees understand the risks of driving while fatigued and the need to comply with safety guidelines.

The letter was written in response to the board's investigation of an October 16, 2005 accident that occurred on Interstate Highway 94 near Osseo, WI. The accident involved two major collisions. First, a Whole Foods truck-tractor semitrailer combination unit rolled over. Then, a motorcoach collided with the wreckage of the Whole Foods truck. Traveling in the motorcoach were marching band members from Chippewa High School. This collision, which occurred just before 2 a.m., killed the motorcoach driver and fatally injured four passengers. Thirty-five passengers received minor to serious injuries. The Whole Foods truck driver received minor injuries.

"The National Transportation Safety Board determined that the probable cause of the truck-tractor semitrailer rollover, the precipitating event in the accident sequence, and the motorcoach's subsequent collision with the truck, was the truck driver's falling asleep at the wheel, drifting from the roadway, and losing control of his vehicle," the letter stated.

The board's letter added that the truck driver failed to take "full advantage of adequate rest opportunities provided to him during his off-duty time and, as a result, obtained inadequate and disrupted sleep prior to the accident."

During the investigation, the driver admitted that in the two days before the accident, he had only 12.5 hours of sleep. "The driver had the opportunity to obtain more sleep in the two days because he was off duty for about 20 hours," the board pointed out in the letter.

The NTSB has asked Whole Foods to respond to the board's recommendations within 90 days of receiving the letter, which was issued Feb. 2.