Which of the following search patterns are considered drifting patterns?

The identification of drifting search patterns is important in search and rescue operations. Drifting patterns are typically used when the subject of the search is believed to have drifted due to environmental factors such as current and wind.

The sector search and the expanding square search are both designed to cover an area effectively while accounting for drift. The sector search allows for searching in a fan-like manner from a central point, which can be adjusted based on the suspected drift of the target. Similarly, the expanding square pattern incrementally widens the area searched, allowing for systematic coverage while factoring in how the target may have moved during the time after it went missing.

These methodologies are based on the understanding that targets can be displaced from their original location due to external forces, making them suitable for situations where drift is a consideration.

Other patterns mentioned in the options do not primarily focus on drift. For instance, the grid pattern and circular pattern are more structured and not inherently adaptable for drift, while the line search and sweep search are linear approaches that lack the flexibility to accommodate drift effectively. Likewise, parallel search and pattern search also do not focus on drift as their main operational principle.