While the concept of a fleet shadower had some promise, the resulting designs were soon overtaken by wartime developments in airborne radar.

[1] Five companies showed interest: Percival, Short Brothers, Fairey Aviation, General Aircraft Ltd and Airspeed.

The AS.39 was a high-wing, semi-cantilever, strut-braced (on the outer panels) monoplane with wooden wings and tail unit and an all-metal monocoque fuselage.

Four small 130 hp (97 kW) Pobjoy Niagara V seven-cylinder air-cooled radial engines were mounted on the wings.

Airspeed were asked to respond to a proposal to re-engine the aircraft with two Armstrong Whitworth Cheetah XI radial engines and add rear-facing machine guns.