The Ca.603 was derived from the training two-seater Ca.602 but differed in having a smaller wing surface and a more reinforced structure, with sturdy interconnecting uprights between the upper and lower wings.

The wings were of the same opening, based on a wooden two- sided beam; the leading edge and the end were covered with plywood, while the rest of the wing was covered in canvas.

The wings were connected to each other by tubular steel uprights stanched and braced by tie rods; the fairing cart was fixed, with independent wheels, with the swiveling rear wheel and open steering position.

[1] In tests conducted between November and December 1940 the acrobatic performances were judged excellent, except in the figure of the screw probably due to the excessive size of the tail plans.

However it was judged as the best acrobatic airplane in existence; however, they proposed changes concerning the change of the wing profile with the progress of the passenger compartment, and also possibly the modification of the vertical embedment both in length and in the design.