Better SOS Devised for Avalanches

Rescue crews searching for skiers, snowboarders and hikers buried by avalanches have to act fast--the difference between life and death is measured in minutes.

A researcher says he’s developed a computer program that could help crews get to avalanche victims wearing radio beacons much more quickly than current methods allow.

“In traditional searches, they’re really not communicating,” said Rush Robinett, a researcher with the Department of Energy’s Sandia National Laboratories in Albuquerque, N.M. “They may be yelling, saying ‘I see something!’ But they’re not really taking the information and quantifying it.”

By using lightweight radios, global positioning receivers and pocket computers programmed with robotic search algorithms, as few as four searchers could zero in on a buried skier, Robinett said.

In computer simulations, Robinett’s method found victims four times faster than simulations of any published search scheme now in use.

Time is critical. The American Assn. of Avalanche Professionals says of the people who survive the violent ride of an avalanche, 90% are alive after the first 15 minutes; 50% survive after 30 minutes; after 45 minutes, only 8% are still living.

Thirty-two people died in avalanches in the United States during the 1998-1999 season--the most since the modern era of record keeping began in 1950, according to the Colorado Avalanche Information Center.

When someone is buried by snow, a traditional and time-consuming rescue method is to search a large “grid” area with steel probes.

If a person is wearing a radio transmitter, searchers can home in on that signal. But Robinett said most current techniques are not that advanced and don’t combine the electronic information all the searchers are getting, as his computer program does.

“They’re in essence doing it individually,” Robinett said.

His computer program enables small devices to “talk” to one another. Each device continually informs the others of its position and of the strength of the signal received from the sought-for source --the buried person’s radio transmitter. The steady stream of data from multiple sources allows search teams to refine the direction of the search.

“You’re trying to take data from multiple searchers and combine it together such that you can get a better picture of what you’re looking for,” Robinett said.

Ethan Greene of the Utah Avalanche Forecast Center said he wasn’t familiar with Robinett’s program but noted, “Having units that are communicating versus just receiving a signal is potentially more useful.”

Robinett originally developed his program for the Department of Defense to help a swarm of tiny robots find the source of a chemical or biological attack.

Finding the location of a radio-frequency sender and finding the source of a chemical attack turned out to be remarkably similar, Robinett said.

The program is being prepared for patenting and could be licensed for use in avalanche rescues.

Even with advanced search techniques, experts warn back-country enthusiasts they shouldn’t count on getting rescued if they’re swept away. They advise people to avoid avalanche-prone areas--mountain slopes between 35 and 45 degrees (exactly the types of hills people like to ski) where a lot of new snow has accumulated, combined with rapid warming and melting.

“It’s a small chance you’re going to get recovered,” said Greene of the Utah avalanche center. “The best thing you can do is to realize when you’re getting into avalanche terrain and not get caught at all.”