Start with the graphic below. While I make no claims for its precision, it is a useful approximation of the problem statement.
The graphic above shows the approximate maximum and minimum range associated with the fuel estimated to be on board MH370 at the time of the last radar contact West of Penang. The approximate radius of the maximum range, blue circle, is 2850 nm. The approximate radius of the minimum range, black circle, is 1100 nm. The red line is the 6th (00:11) Inmarsat arc.
The surface area between the maximum and minimum ranges is approximately 22 million square nautical miles. The distance along the 7th arc between 26S and 40S is approximately 1200 nm. If a very generous search width of 100 nm is used, the area of the 7th arc search as defined by the Inmarsat data is approximately 120000 square nm. It is clear that the Inmarsat data reduces the search possibilities by factor of almost 200, or a factor greater than two orders of magnitude. Two orders of magnitude is a huge reduction.
How can anyone possibly claim the Inmarsat is not extremely useful??
