A satellite launching procedure known as air-launch is modeled and simulated at the staging phase, where a reusable unmanned aerial vehicle airlaunchs a second (rocket) stage. The airlaunch is modeled as a hybrid system with instantaneous jumps. This paper presents the effects of the variations in mass, inertia and aerodynamic coefficients on the stability of the airlaunch system at the stage separation. The airlaunch phase implies on perturbations on aerodynamic forces and moments that may bring the system unstable. For this reason a robust conditional integrator controller is designed with the objective of stabilizing the system during the airlaunch. Performance of the proposed control algorithm is illustrated through computer simulations.