same spanwise distances dz 22 between excitation locations 22 of rows 20 a f within all groups 21 a and 21 b however a distance dx between the rows 20 a c seen in chordwise direction x remains constant within the first row group 21 a with a value dx 20 _ 1 for the next group 21 b of rows 20 d f of excitation locations 22 dx skips to dx 20 _ 2 p u00b7 dx 20 _ 1 with p gt 1 p 2 being particularly preferred because this value helps to avoid disadvantageous nonlinear generation of nocent vortices the general expression then is dx 20 _n pn u2212 1 u00b7 dx 20 _ 1 it may be noted that in fig3 and subsequent figures the groups 21 a and 21 b of rows 20 a f of excitation locations 22 are shown in a shortened way for reasons of ease of representation as can be seen from fig2 and 3 the excitation locations 22 are arranged such that the benign primary disturbance 24 is repeatedly excited by excitation locations 22 this benign steady primary disturbance 24 sustaining the laminar flow is maintained as a longitudinal vortex respectively cross flow vortex on such a high amplitude level that unsteady secondary disturbances which may initiate turbulence and which otherwise are amplified by nocent primary disturbances in streamwise direction are suppressed or at least stabilized fig6 and 7 show an aircraft 10 having.