Proof
I'm a little fed up of the constant drip feeding from the local authorities. It seems every day they've located yet another large piece of the jet, first it was with the mk1. eyeball, now it is with sonar.
It is reminiscent of the constant press gatherings of MH370 which were half truths and lies just to make it look like they had been busy and we're making progress. When I see proof, I will believe them. However I have a feeling they know only a very general area of where the jet is based on floating debris, and nothing more.
A culture where saving face and looking all knowing is not conducive to a professional and accurate recovery mission nor subsequent investigation.