This is where the Boeing 777-200 is likely to have run out of fuel and crashed, according to the analysis by the UK company Inmarsat and British aviation experts of hourly signals sent automatically from the aircraft to Inmarsat’s orbiting space vehicle. More promising still, it is where signals, assumed to have come from the locator beacons attached to the aircraft’s “black box” flight recorders, were picked up on April 5 and over the following days by an American “pinger locator” being towed by an Australian navy vessel, the Ocean Shield.