Abstract
Airplane in contemporary typical transport means, especially in Japan has become indispensable on going to the abroad. Although modern airplane is said as safety, it is evaluated by the accident rate in standard. And accident rates, which are evaluated, do not have been clearly demonstrated. It is also said to be not safe there because the airplane can't stop in general. Therefore, it is use the phrase that the airplane has to avoid the accident. Almost airplane that fly in usual is automated, big difference is not there exists a different elements between Boeing and Airbus steering design in the process up to the crash. It is the presence or absence of the concept of the trim. It is the differences that we entrust either human or machine (, but not both) the way of crisis avoidance in flight envelope. So I announce the importance and future of the usability of the concept of trim.
