An apparatus for using acoustical ranging means and optical ranging means in conjunction for avoiding an undesired firing of a weapon, comprising first acoustical ranging means, second optical ranging means, central evaluating and control computer means operatively connected to said first and second ranging means, said second ranging means comprising laser beam transmitter means, scattered laser light receiver means, and signal processing means operatively connected to said light receiver means for processing scanned images, whereby signals representing image points outside a firing reach define a firing horizon, whereas signals representing image points within the firing reach are used to define a target silhouette.