While only one was built due to material constraints, the FMA 21 served as an advanced training aircraft for the Argentine Air Force (FAA) from 1943-1945.

Due to souring politicial relations between Argentina and the United States, FMA decided to use their experience with the North American NA-16 in service with the FAA to develop their own domestic fighter,[citation needed] so the FMA 21 was heavily based on the fuselage of the NA-16.

[2] The FMA 21's fuselage consisted of welded chrome-molybdenum steel tubes covered in a duraluminium coating.

The cockpit had a sliding all-acrylic canopy and was configured for tandem control.

Related development Aircraft of comparable role, configuration, and era