Originally Posted by promani
Many years ago I was taught that in any search exercise, you always start at the LKP and work outwards from there, allowing of course for any info that may direct the search in a particular direction.
Seems to me that is exactly what was done. 15,000 km^2 is a lot of area to search, so BEA was very interested in any way to reduce that area (for Phase 3). The drift study seemed like a plausible way to do that, so they arranged for some people with drift experience to work on it. The result was the search box for Phase 3. In hindsight, the lack of detection in the search box made it likely (now clear) that the drift study was wrong (currents at this site are unpredictable), but at the time there were people who agreed with the decision to use this data to focus the initial search, while others believed (correctly, if confirmed by the FDR) that an upset A/C could never have made it that far from LKP.
If this had been done last year, then maybe we would now know what really happened that fateful morning. It seems that it took the Russians to enlighten the French on a likely crash site.
Hindsight is 20/20. I'm not sure how much influence the Russian experience had on the Phase 4 search. My understanding is that a brute force search of the remaining 10,000 km^2 was planned, starting with the part within 20nm of LKP. The rational for the 20nm is contained in the Metron analysis, and is based on the sort of aerodynamic considerations that have been much discussed here. I am sure that some will argue that the aerodynamics should have been given more weight at Phase 3.
http://www.bea.aero/fr/enquetes/vol....h.analysis.pdf
Also we can exclude the oil slick now, as I hinted awhile ago?
In the drift analysis, the pollution spot is discussed on pages 134-5. Here they explain how they backtracked the spot. Oil slicks are known to respond more strongly to wind than current, because they have no projection below a very thin surface layer that is wind driven. The report states that oil typically moves at 3-4% of wind speed, and that the wind was strong from the north. The backtracked position, based on wind and current, displayed in figure 27 (from yellow dot, back to orange dot), was based on down grading the motion to 2% of wind, as discussed on page 135. If they had stuck with 3-4%, I think the result would have been very close to the now known debris location. So, it's probably premature to say that the spot is unrelated.
http://www.bea.aero/en/enquetes/flig...oup.report.pdf