The author employs a modified \(\delta_c\)-model of fracture (see [A. A. Kaminskij, “Fracture of viscoelastic bodies with cracks”, Naukova Dumka, Kiev (1990)]). The size of the prefracture domain near the moving crack front is assumed constant. Besides, the safe loading of orthotropic viscoelastic body with crack is studied under plane deformation. The values of external load are found under which the crack does not grow.