Search Pattern Comments 1. - Parallel Track Pattern (Stage 2 search, secondary-response). 2. - Expanding Square Search Pattern. 3. - Sector Search Pattern. 4. - Custom Search Pattern: Track Line (Point-to-Point) Search (Stage 1 search, immediate-response) ---------------------------------------------------------------- 1. - Parallel Track Pattern: (Stage 2 search, secondary-response) Parallel track patterns are normally used when: a) The search area is large and the terrain is relatively level, e.g. desert and maritime areas; b) Uniform coverage is required; and c) The location of the target is not known with any precision. Search legs are aligned parallel to the long axis of the individual search area. The pattern is best used in rectangular or square areas. It is a very suitable pattern for a search conducted over water. The search aircraft proceeds from one corner of the search area maintaining parallel tracks, the first of which is at a distance equal to one-half the track spacing from a side of the area. Successive tracks are maintained parallel to each other and one track spacing (S) apart. This type of search may be carried out by one aircraft or by several aircraft following parallel tracks or each searching smaller rectangular areas separately. When aircraft search hours and adjacent traffic permits, turns will be conducted outside the search area boundaries. This allows observer rest and crew position changes. Geographic Coordinate System: Latitude-Longitude WGS84 ---------------------------------------------------------------- 2. - Expanding Square Search Pattern This procedure is referred to as an expanding square search as it begins at thereported position or most probable location and expands outwards in concentricsquares. It is a very precise pattern and requires accurate navigation. To minimise navigational errors, the first leg is usually oriented directly into the wind. The square search pattern is used when the target is known to be in a relatively small area, no more than 15-20 NM from the start point. The first two legs are travelled to a distance equal to the track spacing (S) and every succeeding two legs are increased by another track spacing length. Turns may be to the left or right, depending upon the observer positions. For successive searches, the direction of the search legs should be rotated by 45 degrees. The final track should be the same as the initial search track from the start point. The number of search legs may be 5, or, increasing by increments of 4, 9, 13, 17 etc. Scanning should start at a distance of one track spacing (S) before reaching the most probable position to avoid leaving an area not scanned near the start point. Observers should be briefed to pay particular attention to the areas outwards of each turn to avoid leaving areas not scanned. The search should be planned so that, whenever possible, the approach to the most probable position, and the first leg, is made into wind. Geographic Coordinate System: Latitude-Longitude WGS84 ---------------------------------------------------------------- 3. - Sector Search Pattern This procedure is used when the position is know or the searh area is not extensive. The sector search pattern is simple to execute with accurate navigational equipment. A high Probability of Detection (POD) is obtained near the target center. A floating datum marker will automatically follow the water current when searching over water. Geographic Coordinate System: Latitude-Longitude WGS84 ---------------------------------------------------------------- 4. - Custom Search Pattern: Track Line (Point-to-Point) Search (Stage 1 search, immediate-response) The track line search is normally employed when an aircraft or vessel has disappeared without a trace. It is based on the assumption that the target has crashed, made a forced landing or ditched on or near the intended route (track) and will be easily seen, or that there are survivors capable of signalling their position by a flashing lamp or other means. The track line search consists of a rapid and reasonably thorough search on either side of the intended route of the target, normally at a height of 1000 to 2000 ft during day or at 2000 to 3000 ft at night. A track line pattern is often used as an initial reaction to a distress situation, the second, intensive phase being introduced on the failure of the track line search. Aircraft and ships following the same route as that of the missing aircraft or ship should be asked if they are available to divert to assist in the search for the target. For ships, this will mean diverting to intercept the most probable track line of the target. For aircraft, this type of search should be regarded as additional to searches by SAR units, as an enroute aircraft may not be entirely suitable as a search platform due to its performance, configuration, endurance,navigational capabilities or lack of observers. Geographic Coordinate System: Latitude-Longitude WGS84 ----------------------------------------------------------------