After the German invasion of Czechoslovakia in March 1939, in an increasingly tense political situation, the Polish Air Force proposed to requisition from the Bulgarian order of PZL.43As. A short-sighted decision by the military authorities, afraid of penalties, was to fulfill the order (the penalties would have been less than the worth of two aircraft - about 440,000 zlotys). The first PZL.43As were delivered to Bulgaria in June 1939, the last of 36 in August, just before World War II began. Along with 12 PZL.43s and two PZL.43As delivered by Germany in 1940, these gave Bulgaria a total of 50 aircraft.