  Upon decreasing the Reynolds number, plane Couette flow first forms
alternately turbulent and laminar oblique bands out of featureless turbulence
below some upper threshold R_t. These bands exist down to a global stability
threshold R_g below which laminar flow ultimately prevails. We study the
fragmentation and decay of these bands in systems that are extended enough for
several bands to exist. We use direct numerical simulations appropriately
tailored to deal with such large systems during long enough durations. We point
out a two-stage process involving the rupture of a band and next its slow
shrinking. Previous interpretations of turbulence decay in wall-bounded flows
within the chaotic transient or spatiotemporal intermittency paradigms are
discussed.
