In Airbus there are a lot of warnings that tell you gear is not down. Did the crew activate approach? Did the landing memo appear? If it did did they look at it? Ldg Gear DN if it is green then the gear is down and locked. Did the SD display wheel page? If it did then at least one LGCIU did it show green? Now that the CVR is found it will reveal their activity from TOD to all the way down.