At 11.10pm, a series of problems began: the autopilot disengaged, a key computer system switched to alternative power, and controls needed to keep the plane stable were damaged.

On the basis of control scheme of autopilot, control law of stable loop and guidance law of automatic guidance system are given. Moreover, pro-proportional guidance law is realized by computer.

But now the parameters of digital autopilot system can be easily designed, changed and loaded at real-time, at different flying states and at different Mach Numbers by missile-borne computer.