- Role: Bomber
- Dimentions: Wingspan 12.92 m, Length 9.27 m, Height 3.44 m
- Engine: 1 x BHP (230 hp)
- Armament: 1 x 0.303in Vickers machine gun, 1 or 2 x 0.303in Lewis machine guns, 460 lb of bomb payload
- Crew: 2
- Number in service: 42
- Country of production: Great Britain
- Years in service: 1918 – 1932
The first 42, 2-seater bombers of this type were received between 1918 and 1920. The Airco de Havilland D.H. 9 was a variation of D.H. 4 designated for bombing missions and fitted with a 230 HP engine. Other than the ability to transport a payload up to 460 lbs of bombs, the D.H. 9 were also equipped with 2 machine guns: a fixed forward firing Vickers for the pilot and a revolving Lewis for the observer.
They were mainly used by the Naval Flying Corps during the Asia Minor campaign. According to official records, at least 6 of them were modified to hydroplanes in 1926 and small numbers remained in service until 1932 for training purposes.