A search pattern is a system which is used in a search to facilitate the most efficient, effective, and successful search possible. Several companies design software which can be used to devise search patterns, and it is also possible to map one out by hand. When people set out on a search, they almost always stop to create a search pattern first, for reasons which range from safety to a desire to avoid disturbing the natural environment.
Several goals need to be accomplished with an effective search pattern, and these goals can vary, depending on the purpose of the search. Identifying an area of interest and ensuring that it is fully covered is critical, of course, as is the decision to take steps to preserve the environment where the search is occurring. Preservation ensures that signs aren't destroyed in the process of the search, and that the search does not disrupt people or animals which may live in the area being searched.
Time may also be a factor, as some situations such as missing persons are time-critical. Another issue surrounds changes in the environment which may obscure the search, such as a prolonged period of time between the search and when the objects was last sighted, or severe weather which would make it hard to find the victims of an avalanche.
When searchers are looking for missing or lost people, they use all information available to estimate the most likely position of the missing persons, and they create a radiating search pattern which focuses on this area. Usually, the lines of the pattern overlap slightly, so that each area gets two passes. Search patterns can also be used to look for forensic evidence, minerals, archaeological materials of interest, and so forth.
Airplanes, boats, and people on foot can all be used to execute a search pattern. Airplanes and boats are often the easiest objects to search with, because a very precise overhead course can be set and followed. Using transponders on the craft, the pilot or captain can ensure that every part of the grid is covered, and provide accurate information once the object or person of interest is found. Airplanes and boats can also take advantage of tools like thermal cameras, radar, and so forth to tease objects out of a crowded and vast environment.
Searchers on foot, horseback, car, or bicycle may need to make allowances to cope with the terrain. While this type of search can ensure that every inch of the ground is covered, which can be critical when searching for objects which are hard to identify, it also requires a lot of energy, manpower, and time. Hand searches of this type are sometimes conducted when the search area is small, or when the overhead search pattern has identified an area which could bear closer scrutiny, such as part of a hillside with signs of ski tracks, or an area of disturbance in the ground.