In order to compute flaw echoes, semi-analytical models commonly use scattering coefficients deduced from plane-wave
approximations for incidence and observation waves. The proposed approach aims at improving the accuracy of methods used in
the ultrasonic NDT module of the Civa simulation software. It relies on a representation of the ultrasonic field as a sum of rays,
where plane wave approximations are applied to each ray, as opposed to the total field, allowing more accurate echo predictions.
Several cases that illustrate the improvement brought by this new method are presented, with comparisons to results obtained by
a finite element model.