The Diploma Thesis concerns investigation of icing effects at L 410 NG aircraft. The aircraft is certified under FAR/CS/AP-23 Commuter category. An analysis was performed for existing Pneumatic De-icing Boots System at the wing area according to three flight configurations and icing conditions referring to document Part 25 Appendix C and O. The analysis was done by CFD solver FENSAP-ICE for various runs with respect to the icing envelope. Cases were assigned as two 2D cross-sections situated at the aircraft’s wing aileron part. Cross-sectional Reynold’s number oscillate between 4.5–8.5×106. Automatic operation of Pneumatic De-icing Boots System was proposed. Attention was paid to the ice accretion aft to the Pneumatic De-icing Boots System. The Appendix (Příloha) P6 contains an English written Article concerning main Diploma Thesis sections.