from that same BBC conversation, see BBC hyperlink above ... crash location, but if it is where this debris has been found then it sits on a boundary where the ocean floor is more like the Alps, very rugged and contoured. "That area borders a large, deep plain about 3km down." Dr Simon Boxall said an A320 could easily "slip through the cracks" of the ocean floor in the area."This is a very soft sediment area and wreckage could sink very quickly,so they need to find it fast," he said. The ocean floor ridges could also act to block signals from the black box pinger, and sonar from vessels searching for the wreckage, ...