Once the scientists at CSIRO had generated the probability distribution for the plane’s last known location on the 7th arc, the next question they had to answer was: how far did the plane travel from that point before it impacted the water? As we've discussed previously, their goal was to define a search box within which the plane was likely to be found. The plane’s location along the 7th arc defined the length of the rectangle, and the distance it could have traveled from the 7th arc would define the width of the search box. So the question of how far the plane could have flown after the last transmission depends on what the investigators thought was going on with the plane at that moment. They decided that, based on the nature of the Inmarsat signals, the plane had mostly run out of fuel and had already started its inevitable descent into the ocean. But had it plummeted steeply, or taken a long, gradual glide? More information at deepdivemh370.com.