A numerical analysis of boundary-layer stability over the cone–cylinder–flare geometry is conducted at Mach 6 and a Reynolds number of [Formula: see text] in order to investigate the role of wall-to-recovery temperature ratio similarity in hypersonic boundary-layer transition. The study compares typical flight conditions with wind-tunnel experiments to assess differences caused by the missing wall-temperature similarity parameter. A second wind-tunnel case with a cooled wall is studied as a pote