Recently, scale, speed and other performances of aircraft have increased and improved. Especially the active control technolgy (ACT) has contributed much to the improvement of performances. Such sophisticated aircrafts operate very well, when all the functions are normal. However, once failures occur in the functions, their normal operations can not be guaranteed, and the accommodation of failures and assurance of safety may require very quick, accurate and complicated restoring operation far beyond human ability. In these circumstances, control systems which automatically restructure themselves to accommodate failures and restore safety and performances, are desired. In this paper, let us suppose that vertical tail is broken in some ways and all the control surfaces are hardover because of failure of the hydro-pressure system. In this case, we study first the effects of vertical tail break on dynamic characteristics of the aircraft and effectiveness of thrust control using optimal regulator. Next we design a restructurable control system which is composed of parameter identification and optimal regulator subsystems. These studies and designs are conducted through computer simulations using a model of a large scale transport (Boeing 747).