The invention relates to a guide vane segment for aircraft gas turbine, which extend along a respective circular arc and together form an annular section, wherein, in the radial direction between the outer shroud and the inner shroud, a plurality of guide vanes are arranged adjacently in the peripheral direction, the outer shroud and the two sealing walls form a trough-like profile in longitudinal section, wherein, at the axially front or/and rear sealing wall element(s), at least one relief gap with a main section is provided, which extends substantially radially inward, starting from a radial outer edge of the respective front or/and rear sealing wall element(s) along the sealing wall element. According to the invention, it is proposed that the relief gap has at least one additional section that adjoins the main section radially inward, wherein the additional section is formed by at least one curved subsection.