By 6 April 1941, the VVKJ had been almost completely mobilised, and consisted of four air brigades with more than 423 aircraft of Yugoslav, German, Italian, French, Czech and British design, including 107 modern fighter aircraft, and 100 modern medium bombers. Other than a small number of locally made Rogožarski IK-3 fighters, almost all the modern aircraft available to the VVKJ were of German, Italian or British design for which limited spares and munitions were available
The Yugoslav aviation industry was quickly harnessed by the RLM and absorbed by major German producers. During June, Ikarus AD became part of WNF as its Werk VII. Under new rulers, it manufactured tail units, rudders and horizontal stabilizers for late models of the Bf 109. As part of diversification of the German aircraft industry, in Slovenia several factories were established and others switched their production programme to support the war effort. These included VDM Luftfahrtwerke Steiermark in Tezno, near Maribor (propellersand parts for DB 605 engines), KIG-Aβling in Jesenice 
Type No April 1941 Remarks
Messerschmitt Bf 109E-3 61
Hawker Hurricane Mk I 47 At least 3 were captured by the Germans, later delivered to Rumania
Hawker Fury Mk II 30 At least two were captured by the Italians 1941
Ikarus IK-2   10 German units captured four IK-2 fighters (2103,2104,2111,2113), and one , No 2106 was found damaged but repairable on the war airfield in Bosnia. The planes were overhauled in repair workshops in Sarajevo and Zemun. IK-2s were given to the newly created Croatian Independent State air force.
Rogožarski IK-3
11 Two IK-3 were probably captured by the Germans (one registered GP+IK and the other 5+7) and one of them at least was tested at the Rechin test centre.
Avia BH-33E   6 Destroyed during April 1941
Dornier Do 17Ka 69
Savoia-Marchetti SM 79-I  40 One was captured (No. 23 or 25) later taken over is taken over by the Croatian Air Force
Bristol Blenheim Mk I   61
Hawker Hind Mk I 2
Caproni Ca.310 12
Breguet 19                                                             120
Messerschmitt Bf 108   13
Potez 63 2
Potez 25     120
Fieseler Fi 156   10
Bücker Bü 131 Jungmann  60
Avia BH-33     5
Rogožarski SIM-XIV-H 15-16
Ikarus ŠM   3 ? 4 ? captured by the Italy
Dornier Do 22kJ  12
Rogožarski PVT  64 Fifteen PVTs captured by the Germans as a result were presented to the newly formed Air Force of the Independent State of Croatia. Later some of these were fitted with bomb racks and used as attack aircraft until 1945.
Rogožarski PVT-H  5
Rogožarski SIM-Х 21 The German forces captured three aircraft (one in Zemun and two in Lazarevac). One of these was delivered to the air force of the Croatian Independent State and used until 1943 when it was destroyed by the Srem partisans in emergency landing.
Dornier Do J   10
Ikarus IO  20-21
Rogožarski SIM-ХH    1
Rogožarski R-100 25  1 taken over by Italy, 11 captured by the Germans and then given to the Croatian Air Force
Heinkel HE 8  1
Dornier D    1
Rogožarski SIM-XI 1 During the invasion of Yugoslavia by the Axis the SIM-XI fell into the hands of the Germans and they handed it over to the puppet state, the Independent State of Croatia (ISC) where they designated it under the code 7351. The Croats used it until December 19, 1943, for glider towing, until partisans destroyed it between the villages of Progar and Boljevci when a Croatian pilot landed in order to reattach and lift the hook that had fallen off.
Rogožarski SIM-XII-H   12
de Havilland DH.60 Moth 1
Zmaj Fizir FN     20 Captured by the Germans .20 were used by the Croatian Air Force, taken over from the Yugoslavian Air Force
Zmaj Fizir FP-2   23  7 captured by the Germans, delivered to the Croatien Air Force
Avia-Fokker AF.39
de Havilland DH.89 Dragon Rapide 1 C/n 6332. YU-SAS. Registered 28 July 1936 (UK reg. G-AEKF). Used by Aeroput until 1941. Captured April 1941
Caudron C.449 Goéland 1 C/n 7506.27. F-APKT, used by Aeroput as YU-SATfrom 29/4 1937. Captured by the Germans 1941, CJ+XM?
Spartan Cruiser II 1 C/n 5 Registered G-ACJO 2 Oct. 1933. Used by Aeroput as YU-SAN named "Ljubljana". Taken over by the Air Force April 1941. Captured by the Germans
Spartan Cruiser II 1 C/n 6 Registered G-ACMW 9 May. 1934. Used by Aeroput as YU-SAO named "Susak". Taken over by the Air Force April 1941. Captured by the Germans
Aero A-35 C/n 111-10. Registered Aug. 1935 to Bata Co (OK-ATD), Borovo , to MO Borovo , to MO Karlovac ( YU-PDE). Captured by the Germans
Zlin XII C/n 248. Registered Aug. 1939 (OK-LZQ) to Bata Co, Borovo. (YU-PFT). To Yugoslavian Air Force. Captured by the Germans 1941