Pete, while your intentions are good, for several reasons this doesn't always work out so well in practice.

There are some issues with using "walk ons" in searches. One big problem is sorting out (in a short time frame) those folks who really have some backcountry savvy and survival skills from those who only think they do. Without having spent time with a person in the field it is tough to get a good sense of their experience. A searcher who themselves become lost, hypthermic, injured, or exhausted is no longer part of the solution, but rather they have added to the problem.

Another problem is that even if people are capable of taking care of themselves in the backcountry, they may not understand basic search methods. For example, untrained searchers can misss important clues. Or they may inadvertantly obliterate those clues. Search teams train their members to not look for people, but rather to look for clues. The idea is that if you are looking for people, you might easily miss seeing a subtle clue, but if you are looking for clues you are unlikely to miss seeing a person. Trained searchers are also taught how to document and preserve clues. Those clues can be crucial to narrowing down the search area.

Yet another issue is that untrained people probably aren't accustomed to working in ICS, and may not understand the importance of following the instructions from the search incident management team, and reporting accurately what they did. This can make it difficult to systematically cover the search area. An example from a recent search illustrates this. A bunch of local folks who were untrained but knew the area well were helping. The Ops Section Chief gave them instruction as to which area to search. But the locals had their own ideas about where the lost person was likely to be, and deviated from their assigned area. Unknown to them, that area had already been thoroughly searched. Thus one area was searched multiple times, and Ops had to send yet another team to cover the unsearched area.

However, we can sometimes put walk on volunteers to good use. One example I can think of was an avalanche body recovery (a deeply buried snow machiner who wasn't wearing a beacon). It was a big slide and turned into a major probing operation lasting a couple of days. We checked to make sure they all had appropriate gear, and gave them a quick lesson in how a probe lines works. We then grouped them into teams with an experienced person in charge of each team.