Article 12(2) of the Convention on the High Seas, 1958, reads:
"Every coastal state shall promote the establishment and maintenance of an adequate and effective search and rescue service regarding safety on and over the sea and - where circumstances so require - by way of mutual regional arrangements cooperate with neighboring states for this purpose."
It doesn't say what is "adequate" though! Furthermore...
Both the 1958 Geneva Convention on the High Seas and the 1982 LOS Convention provide that every state shall require the master of a vessel flying its flag, insofar as can be done without serious danger to the ship, crew, or passengers, to render assistance to any person found at sea in danger of being lost and to proceed with all possible speed to the rescue of persons in distress if informed of their need for assistance, insofar as it can reasonably be expected.
In addition, SOLAS requires the master of every merchant ship and private vessel to assist persons in distress and to broadcast warning messages with respect to dangerous conditions or hazards encountered at sea.
Therefore, all we really need these days is to have an aircraft that can fly to the area (this will be known from the new 406MHz GPS beacons that SARSAT uses and are now mandated) and then has the capability to vector in ships in the area to go to the aid of the survivors. Therefore, if we had some to spare, a Herc could do this quite nicely (and deliver some goodies out the back as well). Also, the E-3D would be ideal for this task - less the dropping of goodies (and I don't mean Graham Garden, Tim Brooke-Taylor and Bill Oddie - although the latter would be a good idea!).
Sadly, it is not SAR that is Nimrod's "raison d'etre" - but we can't talk about specifics on that on here.
The B Word