The Couzinet 70, which was larger than its predecessors, was developed originally as a mail plane for use of Aéropostale's South Atlantic service.

[1] It had a relatively high level of fineness, which was a somewhat controversial design choice at that time; the resulting aircraft being relatively difficult and expensive to fabricate.

[5] Structurally, it comprised numerous bulkheads, both primary and secondary, that were connected via wooden strips and covered by plywood.

[5] It had a trapezoidal shape, streamlined wingtips and narrow ailerons, the latter being hinged to secondary spars running parallel to the wing's trailing edge.

Supported by several wooden strips in addition to the spars, the exterior was covered with plywood, the latter being treated with fireproof dope.

Furthermore, it incorporated a special compensating device that was designed inhouse by Couzinet, which broadly resembled the arrangement fitted on the Blériot 165.

[6] Directly behind the cockpit, where the pilot and mechanic were seated, was a small crew rest area containing two couches; aft of this room was a sizable cabin where the navigator and radio operator, along with their assorted apparatus, were located.

A central walkway ran between the tail and this room, which permitted easy access to various elements, which included all of the steering controls, key piping connections, and the fuel cocks.