A sealed bottom in the frame of a cockpit with centered pilot is disclosed for increasing the bulk inside the radome and making it possible to improve the optimization of the volumes. The sealed bottom includes a semi-cylindrical central part having four edges that are parallel in pairs, two curved edges, and two straight edges and a planar peripheral part extending at least partially around the central part. The peripheral part (22) is located in the plane of the straight edges of the central part and linked thereto. This configuration will allow to free up space to increase the number of passengers or reduce the size of the aircraft.