[3] The program requested an aircraft that had an endurance of six hours and be suitable for dive bombing or laying smoke screens.
It could nevertheless be reduced to a width of 4.75 m (15.6 ft) with the wings folded, which made it comparable in size (and weight) to the Loire 130 it was slated to have replaced.
[6] Work on the prototype was nearing completion in June 1940, but the German victory in the Battle of France caused many French military programs to be suspended, including that for the NC.420.
[4] In June 1942 the German Armistice Commission gave permission for the construction of up to fifteen NC.420s to replace Loire 130s that were damaged or destroyed through normal operation, to be built in 1943–1944.
Work was slowed, however, by the use of SNCAC's Fourchambault factory to build wings for Siebel Si 204s required by the Luftwaffe.