The aircraft was developed for the competition organised by Czechoslovak Ministry of National Defence in 1932 to design new airplane to replace old types like Letov S-16 and Aero A-11. Aero A-100 won this competition for being the only type because the other plane, Praga E-36, was not ready in time. For its time it had good speed and was of quite clean aerodynamic shape.
The prototype first flew in May 1933 and the tests continued until October 1933. It went through some modification because of the problem with vibrations of the tail part and also the flight characteristics worsened after the installation of the military equipment. First series of 11 planes was supplied during summer 1934 and following 2. series was taken over by the Air Force in winter and spring 1935.
The machine was used mainly by recon-squadrons (61. - 66.) in reconnaissance role (was able of 5 hours flight on 7/10 power) and by bomber squadrons No. 71, 72, 74 as a light bomber. It served reliably and the pilots liked easy control.
It still served as recon aircraft when the mobilization in September 1938 took place and few were used in the flight school in Prostejov with dual controls.
From A-100 were developed later types A-101 a Ab-101. These were sold to Republicans during the Spanish Civil War.
Two-seat, single-engine biplane. Steel frame of fuselage and tail was covered with fabric (apart of the engine part of fuselage covered with dural panels). Wings had wooden construction covered with fabric. Liquid-cooled vee engine povered two-blade propeler. Fixed undercarriage with tail skid.
| Wing span | 14,7 m - 48 ft 2.7 in |
| Lenght | 10,6 m - 34 ft 9.3 in |
| Height | - |
| Wing area | - |
| Weight empty | 2040 kg |
| Loaded | - |
| Speed max. | 270 km/h - 146 kts |
| Climb | - |
| Ceiling | 6500 m / 21300 ft |
| Range | 880 km / 547 mi |
| Engine | Avia Vr-36 485 kW/650 k |
| Arnament | 2x mk-30 7.92 mm, 2x Su-31 7.92 mm |