320 driver:
My understanding (talking to an avionics development eng) is that the battery life of the FDR and CVR beacons is very conservative. As in most things in aviation, they are built with generous margin to ensure that they meet the specifications in any forseeable circumstances.
Hi,
It was my understanding also until I read lately a paper from the pinger manufacturer. The manufacturer opinion is that the pinger signal is expected to fade very quickly after operating for 30 days. I can't provide the link for it, as I didn't recorded it, but the sense of this statement was very clear: do not expect any signal lasting very long after the designed 30 days. Hence, the accoustic search will stop after 40-45 days because it would be useless to do otherwise.
If the accoustic search is unsuccessfull, the next step would focus on finding the airframe wreckage using adequate means. The BEA first examinations are not ruling out the existence of large pieces of wreckage at the bottom of the Ocean and its a good thing.
The very bad case would have been a shattered field of small wreckage making it almost impossible to precisely locate it but it doesn't fit with the impact clues revealed.