CHEYENNE, Wyo. — A contract that a young man signed releasing a Wyoming-based wilderness training academy from liability before his death on a 2011 backpacking trip to India bars his survivors from suing for damages, a federal judge has ruled.

U.S. District Judge Alan B. Johnson of Cheyenne on Friday dismissed the suit filed by Elizabeth Brenner of Minnetonka, Minnesota, against the National Outdoor Leadership School, based in Lander, Wyoming. Brenner had claimed the school was negligent in the death of her 20-year-old son, Thomas Plotkin.

In a lengthy written opinion, Johnson stated the facts of the case are tragic and heart-rending, especially for a mother who has lost her son. However, Johnson emphasized Plotkin had signed agreements acknowledging that the NOLS program involved inherently dangerous activities and releasing the school from liability.

"Adults contracting to engage in activities that present extraordinary hazards and challenges should not do so lightly," Johnson wrote. The facts of Plotkin's death wouldn't support claims for gross negligence or willful or wanton misconduct, Johnson stated.

According to court records, Plotkin slipped on a wet rock while carrying a heavy pack and fell down a 300-foot ravine into a raging river. His body was never found. The lawsuit alleged that he was among a group of hikers who were walking far ahead of their NOLS program leaders in rainy, dark conditions when the accident occurred.

Johnson noted that Brenner's lawsuit alleged that the Indian government conducted an independent investigation of the accident that concluded NOLS group leaders should have alerted police and villagers immediately to search for Plotkin. The report also concluded that it seemed improper for the group to be hiking through rough terrain during the evening under a light drizzle.

Bruce Palmer, director of admissions and marketing for NOLS in Lander, Wyoming, said Monday that school officials feel a great sense of loss at Plotkin's death. "It's a tragic situation, certainly," he said. "Our thoughts definitely remain with Thomas' family at this point."

However, Palmer said NOLS officials always have felt that the lawsuit was unjustified.

"We're pleased that the court recognized the value of the programming that we do, and recognized the risks that are inherent in these activities," Palmer said.

More than 230,000 people have graduated from NOLS courses since the school's founding in 1965, Palmer said. Programs commonly involve grueling backcountry expeditions.

About 4,500 students each year participate in field-based programs similar to the one Plotkin enrolled in, Palmer said. Other programs involve classroom study on subjects such as wilderness medicine.

Plotkin's was the latest of 12 fatalities involving NOLS students in the history of the school, Palmer said. He said the majority of fatalities happened prior to about 1980. He said no lawsuits against the school stemming from the fatalities have been successful.

Paul D. Peterson, a lawyer in Woodbury, Minnesota, represents Brenner. Peterson said Monday that he's disappointed in Johnson's decision.

"We received the decision on Friday," Peterson said. "We're still reviewing it and also still reviewing our options."