A method for operation of a timber-working device, like a tree harvester head (5), which is configured to perform at least one operation, like cutting a tree, to which is associated a hazard zone (301) includes the steps: of receiving at least one signal from at least one orientation sensor associated with the timber-working device； determining the orientation of the timber-working device based at least in part on the signal from the orientation sensor； determining whether a predetermined location is within the hazard zone based on the orientation of the timber-working device. Also claimed is a timber-working device (5) configured to perform at least one operation having an associated hazard zone (301), the apparatus including: at least one processor configured to receive at least one signal from at least one orientation sensor associated with the timber-working device； determine the orientation of the timber-working device based at least in part on the signal from the orientation sensor； determine whether a predetermined location is within the hazard zone based on the orientation of the timber-working device.
