September 3, 2008 By Tom Patterson
During a visit to his vacation home in Green Valley Lake, Calif., in the San Bernardino Mountains, retired educator Dean Christy decided to go for a hike in the crisp winter air. But soon after he ventured out into the rugged terrain, a storm moved into the area. On Jan. 4, 2008 at 4:15 p.m., the 62-year-old called 911 from his cell phone, reporting that he was disoriented due to limited visibility in dense fog.
Search and rescue (SAR) teams were hastily dispatched to look for the missing hiker. As the hours stretched into days with no success, the San Bernardino County Sheriff's Department's (SBSD) Mobile Mapping Unit joined the operation to produce a variety of maps to assist in the search. The Mobile Mapping Unit created the maps using GIS technology, which helped determine where to concentrate the search for Christy, pinpoint areas already covered by searchers and brief Christy's family about the search's progress. To try to narrow the search areas, GIS was also used to conduct a viewshed analysis of the zone where Christy likely used his cell phone.
"The benefit to having on-site mapping is that we can use downloaded data provided by searchers from the current day to prepare for the next operational period," said incident commander Cpl. Bryan Lane of the SBSD. "In the case of a search and rescue, we use the maps to analyze areas physically covered by personnel in the field and then direct resources into areas not searched yet."
The first SAR team to reach Green Valley Lake to search for Christy was the Rim of the World Search and Rescue Team. They arrived at about 6:30 p.m. on Jan. 4, near the Green Valley Lake campground, located approximately one-eighth of a mile east of the Christy home. They were greeted by freezing rain and heavy winds gusting up to 90 mph. Confinement and attraction tactics were used throughout the night, including emergency vehicle lights, sirens and public-address systems.
During the initial call, Christy told the 911 dispatcher that he was dressed warmly and was prepared to stay outside by taking shelter under a rock outcropping located about 50 feet from where he was making the call. That was the last time anyone heard from him. (At about 10 a.m., Jan. 5, Christy attempted to make a cell call to access his voicemail. The call was not completed, and that was the last time Christy used his phone.)
At about 2 p.m. on Jan. 5, the rain turned into a blizzard that continued until early Jan. 7, dumping nearly 6 feet of snow in the primary search area. During the next eight days, SAR teams from all over Southern California and as far north as Lake Tahoe and the San Francisco Bay Area joined the search. Helicopters and snowcats brought searchers and their equipment into the field. When aviation assets weren't being used for shuttling searchers into the area, field observers would fly during the day when weather permitted, and at night the helicopters were equipped with forward-looking infrared sensors; the pilots wore night-vision goggles that can detect aboveground body heat.
The Incident Command System was used to manage this massive rescue operation; approximately 100 searchers were assigned each day.
Mobile Mapping Unit
When the search for Christy expanded to 30 square miles on Jan. 10, Lane decided to increase the on-site map production capability by bringing in the SBSD's Mobile Mapping Unit. This 40-foot custom motor home contains a generator, two networked GIS workstations, a color copy machine, remote satellite access to the Internet and a large-format Hewlett-Packard plotter for making 36-by-44-inch briefing maps. SBSD personnel staff the Mobile Mapping Unit, and the members include a situation unit leader, a GPS technical specialist and two public information officers. Two additional GIS technical specialists from ESRI joined the
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