DALEK
If he assessed his initial Vis as our (theoretical) 3nms, he would, without further outside influences, expect to see the cliffs at 3nms. When the TANS told him the range was 3nms he would believe it because he "knew" it was right.
As I have stated before - the old stopwatch/speed/time DR backup may have warned him his TANS was wrong. It does get it wrong occasionally and old and not so bold pilots etc......................................................