During the search for MH370, there was something sad about sailors on aboard RN ships, with binoculars, searching for wreckage by looking out to sea. How far can they see with any reliability? Is this next to futile?
DL, I had 27 years carrying out SAR missions (airborne) and much of the time all those expensive sensors are useless, and you are reduced to visual search. Acoustics is useless unless there is an acoustic source, with a usable range.
Radio homers are useless if nothing is emitting. Radar is useless unless something detectable is sticking out the ocean.
Further problems abound (in all oceans and scenarios)...
The sea is full (and I mean full) of junk. All of which will have to be investigated if it is detected within the search area.
In deep ocean, range is massive issue (in terms of fuel and time on task for aircraft and reaction time for ships)
Surface wreckage drifts (50 miles plus a day), expanding the datum.
Sea state has a huge and very variable effect on the efficacy of visual search.
the list goes on but you get my point.
In the case of MH370 the deck was stacked against a quick find from the get go...no datum whatosever, long way from land, no sign of detectable sized wreckage or high visibility survival equipment, very short range and short life acoustic beacon...
So yeah, futile sums it up completely. Still have to try though, don't they?
Better sensors are not the answer (the sensors do what the taxpayer pays them to). The answer is better tracking in the sky and better beacons on the boxes.