"We worked out where the last ping was, and we knew that the plane must have run out of fuel before the next automated ping, but we didn't know what speed the aircraft was flying at – we assumed about 450 knots," said McLaughlin. "We can’t know when the fuel actually ran out, we can’t know whether the plane plunged or glided, and we can’t know whether the plane at the end of the time in the air was flying more slowly because it was on fumes."