Mk 1 Eyeball
In a search like this you need windows. Not Microsoft windows, perspex windows, and eyes looking out of them. A 737 with trained observers would be more use than a P8 in this scenario. Bits of airliner floating about in sea state 6 will not be detected by radar. IR sensors are too limited in field of view. MK1 eyeball is the primary sensor. Been there, done that. But you need a good datum, good assessment of surface drift and luck, lots of luck.