A three-dimensional Euler code for the computation of transonic steady flows using an explicit pseudounsteady method has been vectorized on an array processor (AP 120B) linked to a host computer (SEL 32/77). Computation speed comparable to that of a CDC 7600 computer is achieved by executing strings of vectorized operations in the array processor simultaneously with calculations at boundary points in the SEL computer and with data transfers between the mass memory and the host computer. A numerical application is presented for transonic flow in a fan rotor.