Natural laminar flow design was applied to the vertical tail of 120-seat class transport aircraft to reduce \(\textrm{CO}_2\) emissions through drag reduction. While the Reynolds number based on the mean aerodynamic chord of a vertical tail is close to that of a main wing, the vertical tail’s large sweep angle and symmetric airfoil makes natural laminar flow design more challenging. The design was verified experimentally at flight Reynolds number conditions in the European Transonic Windtunnel, and the transition Reynolds number based on the distance from the leading edge to the transition location, considering the effect of sweep, was the largest that has ever been observed experimentally, despite the symmetrical airfoil.