[Aviation Works, National Corp.], but soon ran out of the 109's Daimler-Benz DB 605 engines after many were destroyed during an explosion at a warehouse in Krásné Březno.

The S-199 continued to use the Bf 109G airframe, but with none of the original DB 605 engines available, an alternative power unit had to be sourced.

It was decided that the aircraft would use the Junkers Jumo 211F engine and same propeller type, both as fitted to the Heinkel He 111 bomber.

The Daimler-Benz DB 605 engine allowed for a central cannon mount (Motorkanone in German) that fired through the propeller spinner.

This consisted of a single MG 151 cannon mounted beneath each wing, but this further impaired the aircraft's performance.

[2] Israeli agents negotiated the purchase of Avia S-199s from the Czechoslovak government in defiance of an arms embargo that Israel faced at the time.

Forming Israel's first fighter squadron, the four Avias were assembled and sent into combat for the first time on 29 May during Operation Pleshet, attacking the Egyptian army between Isdud and the Ad Halom bridge, south of Tel Aviv.