When they entered service, the IK-3 suffered from minor equipment and instrument faults, largely caused by deficiencies in the Yugoslav aeronautical industry which had resulted in a mixture of foreign and Yugoslav-made instruments being fitted to the aircraft.
The Yugoslav Minister of War approved the acquisition of a further 48 IK-3s to be delivered in 1941–42.
The operational aircraft were allocated to the 51st Independent Fighter Group at Zemun, six each to the 161st Fighter Squadron (Kapetan Savo Poljanec) and the 162nd Fighter Squadron (Kapetan Todor Gogić).
The IK-3 was then tested against Yugoslav Messerschmitt Bf 109Es in mock dogfights.
The evaluation concluded that the IK-3 had several advantages over the Bf 109E; in particular, the Yugoslav aircraft was more manoeuvrable in level flight, enabling it to quickly get behind a pursuing Bf 109E by making tight horizontal turns.

In its first year of service, an IK-3 was lost when one of the squadron commanders, Kapetan Anton Ercigoj, was making a mock attack on a Potez 25 over the confluence of the Sava and Danube rivers.
After passing below the Potez, he went into a climb with the intention of performing a loop.
His rate of climb was too steep and the aircraft fell into a spin at low altitude and hit the water.
Before the Axis invasion of Yugoslavia in early April 1941, the 51st Fighter Group was placed under the 6th Fighter Regiment, which was responsible for the defence of Belgrade.
The 51st Fighter Group was further reinforced the day before the invasion began, with the 102nd Fighter Squadron equipped with Bf 109Es.
When the invasion began on 6 April, the two IK-3 squadrons had only three serviceable aircraft each.

The invasion commenced with a wave of 234 German dive bombers and medium bombers attacking Belgrade.
Escorted by 120 fighters, the bombers reached Belgrade at 07:00; they were met by the 51st Fighter Group, minus an IK-3 from the 161st Fighter Squadron that had developed engine trouble after takeoff and was unable to engage.
The other five IK-3s were the first to meet the initial bomber wave but they were almost immediately attacked by Bf 109Es of Jagdgeschwader 77.
The pilots of the IK-3s claimed five German aircraft, and one aircraft from each Yugoslav squadron was lost.
Poljanec had claimed a twin-engined bomber and a Bf 109E; when he returned to Zemun in his badly damaged aircraft, he was strafed by a Messerschmitt 110, which further damaged his aircraft and wounded him.
After this encounter, only three IK-3s were serviceable, including the one that had developed engine difficulties prior to the first German wave.

A second wave of German aircraft arrived over Belgrade at 10:00 and the remaining IK-3s were scrambled with the rest of the 51st Fighter Group but the IK-3 pilots claimed no victories.
A joint claim was made during the third German attack at 14:00, a twin-engined bomber by Gogić and another pilot from the 162nd Fighter Squadron.
The following day, the IK-3 pilots made five or six sorties against German bomber formations and their fighter escorts, and claimed three bombers between them.
At 17:00, Milislav Semiz attacked a tight formation of three bombers; his aircraft received 56 hits from return fire, 20 of which were in the engine and propeller, but he managed to land the aircraft.
The return of another IK-3 from the workshops meant that the number of serviceable IK-3s remained at three.

It became difficult to continue activity from the 51st Fighter Group airfield at Zemun due to air attacks, so on 8 April the remaining IK-3s and Bf 109Es flew to an auxiliary airfield at Veliki Radinci, 50 km (31 mi) north-west of Belgrade, where the surviving aircraft of the 6th Fighter Regiment were concentrated.
Poor weather made operations impossible until 11 April, when Semiz shot down a Bf 110 that had strafed the airfield.
Later that day, Gogić and another IK-3 pilot claimed one Ju 87 each during a patrol.
That night, German troops approached within 15 km (9.3 mi) of the airfield at Veliki Radinci and the following day all remaining aircraft of t
When they entered service, the IK-3 suffered from minor equipment and instrument faults, largely caused by deficiencies in the Yugoslav aeronautical industry which had resulted in a mixture of foreign and Yugoslav-made instruments being fitted to the aircraft. The Yugoslav Minister of War approved the acquisition of a further 48 IK-3s to be delivered in 1941–42. The operational aircraft were allocated to the 51st Independent Fighter Group at Zemun, six each to the 161st Fighter Squadron (Kapetan Savo Poljanec) and the 162nd Fighter Squadron (Kapetan Todor Gogić). The IK-3 was then tested against Yugoslav Messerschmitt Bf 109Es in mock dogfights. The evaluation concluded that the IK-3 had several advantages over the Bf 109E; in particular, the Yugoslav aircraft was more manoeuvrable in level flight, enabling it to quickly get behind a pursuing Bf 109E by making tight horizontal turns.
In its first year of service, an IK-3 was lost when one of the squadron commanders, Kapetan Anton Ercigoj, was making a mock attack on a Potez 25 over the confluence of the Sava and Danube rivers. After passing below the Potez, he went into a climb with the intention of performing a loop. His rate of climb was too steep and the aircraft fell into a spin at low altitude and hit the water. Before the Axis invasion of Yugoslavia in early April 1941, the 51st Fighter Group was placed under the 6th Fighter Regiment, which was responsible for the defence of Belgrade. The 51st Fighter Group was further reinforced the day before the invasion began, with the 102nd Fighter Squadron equipped with Bf 109Es. When the invasion began on 6 April, the two IK-3 squadrons had only three serviceable aircraft each.
The invasion commenced with a wave of 234 German dive bombers and medium bombers attacking Belgrade. Escorted by 120 fighters, the bombers reached Belgrade at 07:00; they were met by the 51st Fighter Group, minus an IK-3 from the 161st Fighter Squadron that had developed engine trouble after takeoff and was unable to engage. The other five IK-3s were the first to meet the initial bomber wave but they were almost immediately attacked by Bf 109Es of Jagdgeschwader 77. The pilots of the IK-3s claimed five German aircraft, and one aircraft from each Yugoslav squadron was lost. Poljanec had claimed a twin-engined bomber and a Bf 109E; when he returned to Zemun in his badly damaged aircraft, he was strafed by a Messerschmitt 110, which further damaged his aircraft and wounded him. After this encounter, only three IK-3s were serviceable, including the one that had developed engine difficulties prior to the first German wave.
A second wave of German aircraft arrived over Belgrade at 10:00 and the remaining IK-3s were scrambled with the rest of the 51st Fighter Group but the IK-3 pilots claimed no victories. A joint claim was made during the third German attack at 14:00, a twin-engined bomber by Gogić and another pilot from the 162nd Fighter Squadron. The following day, the IK-3 pilots made five or six sorties against German bomber formations and their fighter escorts, and claimed three bombers between them. At 17:00, Milislav Semiz attacked a tight formation of three bombers; his aircraft received 56 hits from return fire, 20 of which were in the engine and propeller, but he managed to land the aircraft. The return of another IK-3 from the workshops meant that the number of serviceable IK-3s remained at three.
It became difficult to continue activity from the 51st Fighter Group airfield at Zemun due to air attacks, so on 8 April the remaining IK-3s and Bf 109Es flew to an auxiliary airfield at Veliki Radinci, 50 km (31 mi) north-west of Belgrade, where the surviving aircraft of the 6th Fighter Regiment were concentrated. Poor weather made operations impossible until 11 April, when Semiz shot down a Bf 110 that had strafed the airfield. Later that day, Gogić and another IK-3 pilot claimed one Ju 87 each during a patrol. That night, German troops approached within 15 km (9.3 mi) of the airfield at Veliki Radinci and the following day all remaining aircraft of t
Rogožarski IK-3