PURPOSE: To permit the speedy operation, facilitating flight control by multiplying a pilot instruction signal in the degree free from the offset by an automatic control signal and adding the obtained value, in the synthesized control in which manual control and automatic control are synthesized.

CONSTITUTION: A flight control consisting of an altitude controller 1, engine revolution speed controller 2, and a direction controller 3 is provided. In the synthesized control in which automatic control is synthesized with manual control, a feedback signal supplied from an altitude sensor 7b is added with an aimed altitude control signal A, in the altitude controller 1, and the obtained value is multiplied by G1, and a feedback signal in G2 multiplication of the signal supplied from an acceleration speed sensor 7a is added with the control signal, and the signal in Km multiplication of the pilot corrective signal (a) is added with the obtained signal and supplied into a corrective servomotor 5a, and control is performed by a corrective system 6a. Since the pilot signal (a) is added after the multiplication in Km times, the pilot signal is not offset by the automatic control signal A, and the speedy operation corresponding to the pilot's intention is obtained. Similar operation is performed for the engine revolution speed controller 2 and the direction controller 3.