Originally Posted by jimbeetle
Anyway, all that is basically an aside to my main point -- not everything floats -- some hunks of the airframe are somewhere close to where AF447 impacted. And my assumption is that is somewhere not far from the LKP. I guess I still can't wrap my mind around the BEA assumption that the FDR can CVR would drift so far.
I believe that the dominant opinion here on PPRuNe and at BEA, is not that the recorders drifted far from the point of impact, but that the point of impact is not close to LKP. That does not mean that the point of impact is
not close to LKP, just that is it believed to be elsewhere, and that is why the search has been conducted elsewhere.
From what I have learned in this thread, the point of impact is believed by BEA to be somewhere inside of a 40nm radius of LKP, because the position reports were transmitted at 4min intervals and 40nm represents the distance that the a/c could cover in 4min at cruise speed.
The area north and west of LKP has been searched most thoroughly exactly because that is the area where the point of impact was calculated to be, based on backtracking the drift of the floating debris. The drift models are based on the available wind and current data, and assumptions about the exposure to air and to water of the various bits of debris. This approach is based on BEA's belief (from examination of recovered wreckage) that the a/c impacted the water intact, and thus all debris drifted from a single point.
The goal of the search
is to locate the large parts that sank quickly (mostly in place under the point of impact), and then to fan out from that point to find individual items. So far, no debris has been identified on the bottom, so the working assumption must now be that the point of impact is not in the area already searched. Because the area directly under LKP has not been thoroughly searched, the possibility that the a/c is under LKP has not been eliminated.