Cutouts are an integral part of airframe shells. Understanding the effect of cutouts on the buckling behavior of FRP stiffened airframe shells is an essential part of designing these hybrid shell structures. This paper investigated the effect of centrally located unstiffened longitudinal rectangular cutouts with varying size on the buckling behavior of an elastically buckling hybrid airframe shell of a high radius to thickness ratio (r/t) and equipped with end bulkheads. The effect of cutouts on shells is a function of initial geometric imperfections, predominantly in elastically buckling shells. So, the above investigations are carried out both for shells with very small and relatively large imperfection magnitudes. It is brought out that pre-buckling deformations and stress concentration play a dominant role in deciding the buckling pattern and buckling load of shell structures with cutouts. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.