A sector search or expanding square are most likely to be used based a on a known datum - a sector search saturates the datum and the expanding square works outwards from that area.
With a missing or damaged vessel (the type of scenario we are looking at here) where an exact position is not known (hence the need for a search) the CG will normally allocate a search box which will be covered using a creeping line ahead style search - up the stairs and along the corridor, repeat at the other end of the box style if you will.
If you only have a 120 radar, you can only search in the direction you are travelling - if you have a 350 radar you are searching all around. Which do you think gives the best ie most effective and efficient search?