2.1 The decision to provide a stopway and/or a clearway as an alternative to an increased length of runway will
depend on the physical characteristics of the area beyond the runway end, and on the operating performance requirements of
the prospective aeroplanes. The runway, stopway and clearway lengths to be provided are determined by the aeroplane take-off
performance, but a check should also be made of the landing distance required by the aeroplanes using the runway to ensure
that adequate runway length is provided for landing. The length of a clearway, however, cannot exceed half the length of takeoff
run available.