I see that you are referring to the "Sector search" and it can also be that but I don't think it is. The definition below does not include flying the "circular area" which is why I said comms and the pic looks like the nuclear symbol. Also each of those fan blades is 5+ miles. Again according to the definition, the sector search is applied looking for a small object in a well defined area. The plane only made one pass on each direction except for coming and going. Doesn't sound like a search to me.

A sector search, also known as a Victor Sierra (VS) by the US and Canadian coast guards is a search pattern suitable for a small object in a well defined location that covers a circular area centred on a reported position using a route made up of straight line segments that efficiently covers a circular area, and is adapted to account for drift. First the search vessel makes a measurement of the drift speed and direction, using a datum drift marker to indicate the drift in real time. The pattern is steered relative to the datum marker, and the track over the ground may look considerably different due to superposition of drift. By steering by compass and directly towards the drifting datum every third leg, the search vessel drifts the same amount as the datum, which is the assumed amount of drift for the target. If the initial sector search – often started in approximately drift direction – is unsuccessful, a second sector search can be offset by 30° to either side to give better coverage of the same mass of surface water.[1][2]